Lives of the Saints by Alban Butler.
Lives of the Saints by Francis Weninger.
Lives of the Saints by Sabine Baring-Gould.
Short Instructive Sketches from the Lives of the Saints
An Alphabet of Saints by Robert Hugh Benson, Reginald Balfour, and Charles Ritchie.
In God’s Garden: Stories of the Saints for Little Children by Amy Steedman.
Stories of the Saints by Caroline Chenoweth.
Life of Saint Theodore of Sykeon
The Passion of Saint Christopher
Another Passion of Saint Christopher
Irish Passion of Saint Christopher (also here)
Lives in the South English Legendary (free to borrow with registration)
The Golden Legend (and illustrations)
Art & Architecture
The Ovetari Chapel – the Saint Christopher cycle, detail, detail
14C Spanish Retablo
15C Painting, 15C Sculpture, 15C Painting, 15C Painting
16C Woodcut, 16C Sculpture, 16C Engraving, 16C Painting, 16C Painting, 16C Sculpture, 16C Painting
Warburg Institute Iconographic Database
Guide to Christian Iconography: Images, Symbols, and Texts
Kornbluth Photography Historical Archive
Google Arts & Culture
Saint Christopher at the Metropolitan Museum of Art
Post-Biblical Saints Art Index
Sacred and Legendary Art volume II by Mrs. Jameson.
A Handbook of Christian Symbols and Stories of the Saints as Illustrated in Art by Clara Erskine Clement.
A Garner of Saints: Being a Collection of the Legends and Emblems Usually Represented in Art by Allen Hinds.
The Saints in Art with Their Attributes and Symbols, Alphabetically Arranged by Margaret E. Tabor.
Saints and their Symbols: A Companion in the Churches and Picture Galleries of Europe by E. A. Greene.
The Saints in Art by Joseph Maria von Radowitz.
Emblems of Saints by Which They Are Distinguished in Works of Art by F. C. Husenbeth.
Sacred Symbols in Art by Elizabeth Edwards Goldsmith.