Zahid Ismayil oglu Khalilov (Azerbaijani: Zahid İsmayıl oğlu Xəlilov, January 14, 1911, Tbilisi—February 4, 1974, Baku) was an Azerbaijani mathematician (Professor since 1946) and engineer. Being the founder of Azerbaijani functional analysis school, he was elected President of the Azerbaijan Mathematical Society. Khalilov solved the boundary value problem for polyharmonic equations, proposed abstract generalizations of singular integral operators and made some other contributions.
Khalilov was first to consider the abstract equation with an operator satisfying the condition Q2 = I, within the framework of normed rings. The associated theory was a direct treatment of the singular integral equations theory with continuous coefficients within the subject of an abstract normed ring. Khalilov had also translated the Noether theory to the case of abstract singular equations in a normed ring R ux + vS(x) + T(x) = y and gave a general theory of regularizers.
Khalilov also investigated the problems of subterranean hydromechanics applied in development of oil and gas deposits.