Cornelius Høyer (26 February 1741 – 2 June 1804) was a Danish painter, mainly known for his work in miniatures.

From an early age he attended the Royal Danish Academy of Fine Arts, studying under Carl Gustaf Pilo and Louis Tocqué, and later continued his education in Paris where Jean-Baptiste Masse taught him miniature painting.

A visit to Italy in 1767 introduced him to Rosalba Carriera and he learned new skills, including the special technique of painting on ivory.

In 1769, Høyer was appointed Miniature Painter to the Danish Court and the following year he became a member of the Academy.

Visits to several European courts, including those in Stockholm, Saint Petersburg and Berlin, contributed to his increasing international reputation.