Henri Decaisne was a Belgian historical and portrait painter.

Decaisne was born at Brussels in 1799. As early as 1814 he began to study painting under François, and in 1818 upon the advice of David he went to Paris and entered the studio of Girodet, whence he removed to that of Gros. Several pictures by him are at Versailles; among them are the 'Entry of Charles VII into Rouen' (1838), and the 'Institution of the Order of St. John of Jerusalem' (1842). In 1839 he completed his colossal work, ' Les Belges Illustres.' He died in Paris in 1852.