Pierre Émile Cartier (10 June 1932 – 17 August 2024) was a French mathematician.

An associate of the Bourbaki group and at one time a colleague of Alexander Grothendieck, his interests have ranged over algebraic geometry, representation theory, mathematical physics, and category theory.

He studied at the École Normale Supérieure in Paris under Henri Cartan and André Weil.

He is known for the introduction of the Cartier operator in algebraic geometry in characteristic p, and for work on duality of abelian varieties and on formal groups.

In 1970 he was an Invited Speaker at the International Congress of Mathematicians in Nice.