The San Cassiano Altarpiece is a painting by the Italian Renaissance master Antonello da Messina, dating to 1475–1476.

Commissioned for the church of San Cassiano in Venice, it was disassembled in the early 17th-century and the reunited central portion is now housed in the Kunsthistorisches Museum in Vienna.

[1] It is unknown when it was disassembled or why, but it was already in fragments when parts of it were documented by David Teniers the Younger for his Theatrum Pictorium in 1660.

Originally a larger altarpiece, it now comprises only the central panel with the Virgin Enthroned, and four half-busts of saints: St. Nicholas of Bari, Mary Magdalene (or Ursula), St. Lucy and St. Dominic.

The book with three golden balls held by St. Nicholas alludes to the episode in which he gave them to three girls to be used as dowry.