Also see C.S. Lewis's novel, THAT HIDEOUS STRENGTH, where the brain of Merlin is resurrected in order to give power to the agents of N.I.C.E. (the National Institute of Coordinated Experiments).
Actually, the brain is that of a murderer sentenced to death, who has been possessed by a demon or the Devil.
Merlin is in suspended animation. N.I.C.E. wants to revive him to use his occult powers to advance their agenda. To their dismay, Merlin turns out to be a Christian (albiet a somewhat primative and fierce Christian) who sides with the good guys, to the regret of N.I.C.E.
The murderer's possessed brain is destroyed in the final battle between N.I.C.E. and the forces of good.