  We present a generalization of Hilfer derivatives in which Riemann--Liouville
integrals are replaced by more general Prabhakar integrals. We analyze and
discuss its properties. Further, we show some applications of these generalized
Hilfer-Prabhakar derivatives in classical equations of mathematical physics,
like the heat and the free electron laser equations, and in
difference-differential equations governing the dynamics of generalized renewal
stochastic processes.
