SQPN (http://saints.sqpn.com/) is my favorite, go-to site for a quick summary of a saint. It also has a great collection of links at the end of each article.

The 1912 Catholic Encyclopedia (http://www.newadvent.org/cathen/) is generously available online or as a download. The Catholic Encyclopedia has a comprehensive collection of the lives of the saints, listing historical sources and often going in depth, depending on the information that was available at the time. The way the saints are depicted in this volume represent solid Catholic scholarship as of 1912. When I want to know more about a saint canonized by the beginning of the 20th century, this is the first resource I check.

http://www.vatican.va/roman_curia/congregations/csaints/ The Vatican’s Congregation for the Causes of the Saints (part of the Roman Curia) has biographies of the saints and blesseds proclaimed by Bl. John Paul II. For those more recently canonized and beatified, a websearch with the person’s name combined with the word “vatican” often brings up the published biography or the homily for their beatification/canonization.

(Alphabetical Listing )

Don’t forget to check out:

The Catholic Encyclopedia (1912 Edition) for any saint who lived before the 20th century.

SQPN’s easy-to-find short summaries of the lives of the saints.

St. Alphonsa of the Immaculate Conception http://saintalphonsamma.org/St_Alphonsa.html A detailed online biography that includes some of her writings and the history of the shrine dedicated to her, this site is hosted by St. Alphonsa’s congregation, the Franciscan Clarists.

St. Anthony of Padua

http://www.americancatholic.org/Features/Saints/Saint.aspx?id=1413 Accessible biography of St. Anthony; at the bottom of the page is a collection of articles that trace St. Anthony’s life in more detail.

St. Augustine

http://www.augnet.org/default.asp A reference site for all things regarding St. Augustine of Hippo and the Order of St. Augustine, including St. Augustine’s life, writings, times, and legacy.

St. Benedict of Nursia

http://www.osb.org/gen/benedict.html A quick, broad-stroked introduction to St. Benedict

http://www.e-benedictine.com/ A comprehensive guide with detailed information about St. Benedict’s life, rule, medal and order.

St. Bernadette

http://www.biographyonline.net/spiritual/bernadette-soubirious.html

An short overview of the life of St. Bernadette.

http://en.lourdes-france.org Under the section, “Deepen,” this official website of the Sanctuary of Our Lady of Lourdes includes not only the life of St. Bernadette, but profound reflections on the message of Our Lady of Lourdes.

St. Catherine of Siena

http://www.drawnbylove.com/ A comprehensive site for one of the three women doctors of the Church, unique in its many accessible articles on Catherine’s spirituality.

http://www.vatican.va/holy_father/benedict_xvi/audiences/2010/documents/hf_ben-xvi_aud_20101124_en.html Pope Benedict XVI’s General Audience reflection on the life and legacy of St. Catherine of Siena on November 24, 2010.

St. Cecilia

http://www.sacred-destinations.com/italy/rome-santa-cecilia This unexpected resource goes behind the legends associated with Saint Cecilia (and there are several unsubstantiated stories) by examining the one concrete piece of history we still have access to: her home in Travestere, Rome, over which is built a church.

Saints Charles Lwanga, Joseph Mukasa, and Companions

http://www.ugandamartyrsshrine.org.ug/details.php?id=11 The website of the Shrine of the Ugandan Martyrs is currently the most complete resource online in English for the Catholic Ugandan Martyrs, with fascinating details for each individual martyr.

http://www.dacb.org/index.html The Dictionary of African Christian Biography includes many of the martyrs’ stories in its comprehensive index of African Christians.

St. Clare of Assisi

http://www.vatican.va/holy_father/benedict_xvi/audiences/2010/documents/hf_ben-xvi_aud_20100915_en.html A short overview of the life of St. Clare from a homily of Pope Benedict XVI.

http://www.franciscanfriarstor.com/archive/stfrancis/St_Clare_of_Assisi/stf_st_clare_of_assisi.htm The Franciscans have put together an excellent resource here, with an overview of Clare’s life, her rule of life and letters, and reflections on her legacy.

St. Damien de Veuster

http://www.ssccpicpus.com/pag.aspx?In=en&id=87 Biography and resources from St. Damien’s congregation; visit this link for additional resources such as photos and articles.

http://www.fatherdamien.com The Archdiocese of Honolulu’s website dedicated to St. Damien includes photographs of the saint, prayers, and a short video about his life.

St. Edith Stein

http://www.edith-stein.com/?page=start_eng&language=eng

Website includes a brief timeline of the major events in her life, photos, information about the places where she lived and visited, and other resources.

http://www.edithsteincircle.com/academic-biography.html

A website dedicated to the philosophical works of Edith Stein

St. Elizabeth of Hungary

http://www.vatican.va/holy_father/benedict_xvi/audiences/2010/documents/hf_ben-xvi_aud_20101020_en.html Pope Benedict XVI’s informative and inspiring overview of the joys and tragedies of Elizabeth’s life, with a brief application to our lives today.

http://www.encyclopedia.com/topic/Saint_Elizabeth_(Hungary).aspx#1-1G2:3404701993-full An excellent overview of her life from a secular source that reveals not only St. Elizabeth’s charity but also her sense of social justice. This article also makes much of her medieval context comprehensible for people today.

St. Elizabeth Seton

http://www.emmitsburg.net/setonshrine/ In-depth article about her life and legacy.

http://famvin.org/wiki/Category:Elizabeth_Ann_Seton A collection of “Spiritual Gems” from the writings of St. Elizabeth Ann Seton.

St. Frances Xavier Cabrini

http://www.mothercabrini.org/legacy/life1.asp

A detailed description of the life and legacy of Mother Cabrini from the community she founded, the Missionary Sisters of the Sacred Heart of Jesus. 

St. Francis of Assisi

http://www.franciscanfriarstor.com/archive/stfrancis/ The Friars of the Third Order Regular have put together a rich site with a detailed biography of Francis, along with excerpts from his writings and the first biographies written about him.

St. Francis Xavier

http://www.ignatianspirituality.com/ignatian-voices/16th-and-17th-century-ignatian-voices/st-francis-xavier-sj/ The brief overview of his life is followed by links to further resources—including articles and online videos.

http://www.fordham.edu/halsall/mod/1552xavier4.asp

A letter written by Francis Xavier that gives a glimpse into his missionary life in Japan and his thoughts on the Japanese people of the era

Bl. Franz Jägerstätter

http://www.dioezese-linz.at/redaktion/index.php?page_new=872

Contains a short biography and long biography of Franz available for reading online or download, as well as photos.

St. Germaine Cousin

http://www.catholic.org/saints/saint.php?saint_id=52#top A compilation of the few resources available on the life of this humble shepherdess.

St. Gregory the Great

http://www.ccel.org/ccel/gregory Offers a brief biography and digital versions of the saint’s writings. Check out The Catholic Encyclopedia’sextensive biography as well.

St. Helena

http://www.newadvent.org/cathen/07202b.htm The Catholic Encyclopedia has the best overview of St. Helena’s life online.

St. Hildegard of Bingen

http://www.isi.edu/~lerman/music/Hildegard.html Historical overview of her life and works, which includes a detailed description of her major writings, scientific views and musical compositions.

St. Isidore Bakanja

http://www.dacb.org/stories/demrepcongo/bakanja_isidore.html Brief overview of Bl. Isidore’s life.

http://www.carmelite.org/documents/Spirituality/pickmanisidorebakanja.pdf Four-page presentation on his life and spirituality from the perspective of a Carmelite today

Bl. James Alberione

http://www.alberione.org/en The Pauline Family’s website dedicated to Bl. James Alberione’s life and works. Note the link to OperaOmnia,which includes digital copies of some of his writings in multiple languages.

St. Joan of Arc

http://smu.edu/ijas/ The International Joan of Arc Society seeks to offer all things Joan of Arc, including written accounts of her trial, and links to many resources.

http://www.stjoan-center.com/ Comprehensive list of links on St. Joan’s life and martyrdom, including movie clips.

St. John Vianney

http://www.arsnet.org/index_en.php An overview of his life presented by the Shrine of Ars.

http://archive.org/details/TheCureOfArs-SelectionsFromTheWritingsOfStJohnVianney Digital file of excerpts from his writings.

St. Juan Diego

http://www.sancta.org/juandiego.html Brief biography of Juan Diego

http://www.queenoftheamericasguild.org/BriefHistoryNew.html

History of the apparitions of Our Lady of Guadalupe with an explanation of the image.

http://www.sancta.org/nican.html

An account of the apparitions of Our Lady to Juan Diego inspired by the works of an Indian scholar that was originally written in the Aztec language in the 16th century.

St. Kateri Tekakwitha

http://www.katerishrine.com/kateri.html The National Shrine of St. Kateri Tekakwitha offers an overview of her life.

http://www.leveillee.net/kateri/index1.html Kateri Tekakwitha’s relative constructed this website and it offers a detailed biography, quotations from her original biographers, and a number of reflections about Kateri’s influence on us today. 

St. Katharine Drexel

http://www.katharinedrexel.org/Katharine_Drexel.html

Biography of Katherine Drexel and the history of the Sisters of the Blessed Sacrament.

St. Lorenzo Ruiz

https://www.youtube.com/watch?v=uCy4Ba-JbH8&feature=player_embedded A brief  portrayal of the life of St. Lorenzo.

Bl. Louis and Bl. Zélie Martin

http://www.thereseoflisieux.org/the-parents-of-st-therese-fr/ A wonderful site for the entire Martin family, this particular page (and the links on it) offer not only a biography of the couple, but also insights into their important witness to the Church today.

http://www.piercedhearts.org/theology_heart/church_teaching_saints/homily_beatification_Louis_%20Martin_Zelie_Guerin.htm Homily for the couple’s beatification by Cardinal Jose Saraiva Martins.

Bl. Manuel Lozano Garrido

http://the-hermeneutic-of-continuity.blogspot.ca/2010/06/journalist-lolo-to-be-beatified.html   A short introduction to his life.

http://amigosdelolo.com/recursos/BiografiaLolo_18junio2010_ingles.pdf

A biography that is divided into short readable sections to highlight each aspect of his life.

St. Marguerite Bourgeoys

http://www.cnd-m.org/en/st.marguerite/index.php The Congregation of Notre Dame offers this brief but comprehensive overview about St. Marguerite. Check out the links section for more resources. 

St. Marie-Clémentine Anuarite Nengapeta

http://www.dacb.org/stories/demrepcongo/anuarite_mc.html Biography of her life and martyrdom.

St. Mark

http://www.newadvent.org/cathen/09672c.htm Best online article about St. Mark is from The Catholic Encyclopedia.

St. Martin de Porres

http://www.martindeporres.org Brief biography.

Bl. Mary Elizabeth Hesselblad

http://kateriirondequoit.org/ktp/index.cfm/resources/saints-alive/edith-stein-eusebius/bl-elizabeth-hesselblad/  Brief biography of Bl. Elizabeth that explains the circumstances in which Bl. Elizabeth lived.

St. Mary MacKillop

http://www.visitmarymackillop.com.au/index.html

The life story of Mary MacKillop told through a tour of the places of note in her life.

http://www.marymackillop.org.au/ Comprehensive resource on her life and legacy. The interactive website includes video excerpts from the film “Mary.”

Ven. Matt Talbot

http://www.savior.org/saints/talbot.htm Brief biography

http://www.venerablematttalbotresourcecenter.blogspot.ca/ A comprehensive compilation of resources about Matt Talbot’s life, conversion and recovery from alcoholism.  Also includes links to a documentary about his life (Part 1 and Part 2).

Bl. Miguel Agustín Pro

http://puffin.creighton.edu/jesuit/pro/pro_bio.html A collection of photos, drawings, articles, and letters that paint a picture of the unique personality of Blessed Pro. A special section includes photos of his martyrdom.

http://www.thesacredheart.com/sts/pro.htm

Inspiring biography of Miguel Pro

St. Monica

http://osa-west.org/saintmonica.html Brief summary of Monica’s life. The best information we have about Monica comes from her son, St. Augustine. The www.augnet.org site has several pages on her: http://www.augnet.org/default.asp?ipageid=52

St. Noël Chabanel

http://www.wyandot.org/chabanel.htm Straightforward account of his life and death.

http://puffin.creighton.edu/jesuit/relations/relations_35.html The first historical account of his martyrdom in the Jesuit Relations of 1650.

St. Patrick

http://www.xenos.org/ministries/crossroads/donal/patricks_life.htm Excellent overview of his life based on his “Confessions,” as well as the legends surrounding this saint.

http://www.ccel.org/ccel/patrick/confession.html The Confession of St. Patrick online.

St. Paul

http://saints.sqpn.com/butlers-lives-of-the-saints-saint-paul-the-apostle/ From Butler’s Lives of the Saints comes this extensive classic description of the life of St. Paul.

http://www.archtoronto.org/stpaul/index.htm An accessible resource created by the Archdiocese of Toronto to celebrate the year of St. Paul, with a biography, prayers and hymns, and an overview of each Pauline letter.

http://www.americancatholic.org/Newsletters/CU/ac0708.asp An easy-to-read introduction to St. Paul by Ronald D. Witherup, S.S.

St. Peter Claver

http://www.kofpc.org/index.php?option=com_content&view=article&id=57&Itemid=54 

Highlights his work among the slaves, his last days, and one of his letters.  

St. Peter To Rot

http://www.mscperu.org/english/justasking/itorot_martyr.htm Brief biography.

http://www.catholicpng.org.pg/faith/ToRot.html Most in-depth biography available online, with interesting details about St. Peter’s devotion to his family and his Lord.

St. Philip Neri

http://www.archive.org/details/lifeofphilipneri01baccuoft Scanned copy of book,  The Life of Philip Neri by Father Bacci, an Oratorian priest, translated from the Italian.

Bl. Pier Giorgio Frassati

http://www.frassatiusa.org All about Bl. Pier Giorgio. The FAQs are not to be missed, showing how he is a normal person just like us!

http://catholic.net/index.php?option=dedestaca&id=3537&grupo=Faith&canal=Prayers%20%26%20Devotions A light-hearted biography that characterizes the fun, practical-joker.

Ven. Pierre Toussaint

http://docsouth.unc.edu/neh/leehf/menu.html  Full text of the first biography of Pierre Toussaint, written by his friend and originally published in 1854.

http://www.toussaintacademy.org/pierretoussaint.html Captivating biography of Pierre Toussaint.

St. Pio of Pietrelcina

http://www.ewtn.com/padrepio  Comprehensive resource on Padre Pio as a man, Franciscan, priest, mystic and saint. Includes several letters and audio reflections on his life and spirituality.

http://padrepio.catholicwebservices.com/ENGLISH/ENGLISH_index.htm A collection of stories from his life.

St. Rita

http://saints.sqpn.com/pope-john-paul-ii-a-life-of-heroic-humility-and-obedience/  – Address on the 100th anniversary of the canonization ofSaint Rita of Cascia, by Pope John Paul II, 20 May 2000.

http://www.saintritashrine.org/life-of-saint-rita/ The life of St. Rita and the online home of the Society of St. Rita.

St. Rose of Lima

http://www.ewtn.com/library/MARY/bertroselima.HTM

A translation of Cardinal Bertone’s homily for the Feast Day of St. Rose of Lima, 2007.

Servant of God Satoko Kitahara

http://www.patheos.com/blogs/deaconsbench/2011/03/homily-for-march-27-2011-3rd-sunday-of-lent/ Brief overview of Satoko’s life that invites us to allow our encounter with Christ to transform us into proclaimers of the Gospel.

http://www.davidscottwritings.com/satoko.html Captivating account of Satoko’s life. 

St. Teresa of Avila

http://www.biographyonline.net/spiritual/st_teresa_avila.html Introduction to her life.

http://www.benedictinesofdivinewill.org/uploads/3/0/2/6/3026643/autobiography_of_teresa_of_avila.pdf Online or downloadable edition of The Life of Teresa of Jesus: The Autobiography of Teresa of Avila, translated and edited by E. Allison Peers from the critical edition of P. Silverio de Santa Teresa, C.D.

St. Teresa of Calcutta

http://www.motherteresa.org

The official site of MTCC, a center established by the Missionaries of Charity to serve as an authoritative and comprehensive source of information on Mother Teresa. Includes digital audio files and video interviews.

Venerable Teresita Quevedo

http://thirdordercarmelite.wordpress.com/carmelite-venerables-and-servants-of-god/maria-teresa-gonzalez-quevedo/ An accessible biography that highlights Teresita’s devotion to Our Lady

http://www.moscati.it/English/En_Tere1.html Lively, detailed story of Teresita’s life.

St. Thomas Aquinas 

http://www.historyguide.org/intellect/aquinas.html Several links to a solid introduction to St. Thomas Aquinas’s life and writings.

http://saints.sqpn.com/stt03003.htm Detailed, book-length biography by Fr. Placid Conway, OP.

http://www.aquinasonline.com/Links/ Comprehensive resource on his writings and philosophy. The texts page has links to many of his writings available online.

St. Thomas Becket

http://www.newadvent.org/cathen/14676a.htm Best detailed account of Thomas Becket’s life is found at The Catholic Encyclopedia.

St. Thomas More

http://www.apostles.com/thomasmore.html Comprehensive resource on St. Thomas More’s life and writings. Includes digital editions of his writing.

Bl. Victoria Rasoamanarivo

http://saints.sqpn.com/blessed-victoire-rasoamanarivo/ This brief biography is one of the few English resources online for Bl. Victoria. 

Zita

http://www.dmoz.org/Society/Religion_and_Spirituality/Christianity/Denominations/Catholicism/Saints/Z/Saint_Zita/  A list of online resources on this saint.