Juan de Celaya (Valencia, c. 1490 – 6 December 1558) was a Spanish mathematician, physicist, cosmologist, philosopher and theologian.

During his studies he was a student of the Nominalist Gaspar Lax and of Dullaert of Ghent, who exerted considerable influence on the ideas and works Celaya would write.

In 1524 he returned to his native city, and a year later became Principal and Professor of Theology at the University of Valencia, where he played an important role in the reforming the structure of studies.

During his time in France, Celaya was a prolific writer, dealing mainly with the physics of Aristotle, in particular the study of motion.

He was one of the main promoters of nominalist logic and the Oxford Calculators ideas about Dynamics and Kinematics.