In mathematics, there are a number of so-called Deligne conjectures, provided by Pierre Deligne. These are independent conjectures in various fields of mathematics.

The Deligne conjecture in deformation theory is about the category theory structure of Hochschild cohomology. It is now regarded as proved, by Kontsevich and others. It is of importance in relation with string theory.

The Deligne conjecture on special values of L-functions is a formulation of the general hopes for formulae in closed terms for L(n) where L is an L-function and n an integer.

There is a Deligne conjecture on 1-motives arising in the theory of motives in algebraic geometry.

There is a Gross-Deligne conjecture in the theory of complex multiplication.

There is a Deligne conjecture on monodromy, also known as the weight monodromy conjecture, or purity conjecture for the monodromy filtration.

There is Deligne conjecture in the representation theory of the exceptional Lie groups.

There is a Deligne-Langlands conjecture of historical importance in relation with the development of the Langlands philosophy.