In "Friday the 13th Part VI: Jason Lives," Jason comes back to life when lightning strikes the metal fence post impaling his corpse.
Tommy Jarvis visits Jason Voorhees's grave during a storm, intending to cremate the body and end the killer's threat permanently. When Tommy drives a metal post into Jason's corpse, lightning hits the post, sending electricity through the body and resurrecting Jason as an undead revenant.
This film is a major turning point in the Friday the 13th series. Earlier films presented Jason as an apparently human killer, but Jason Lives makes him explicitly supernatural, giving him extraordinary strength and durability. The scene deliberately echoes Frankenstein stories, in which electricity brings a dead body back to life.
A common mix-up is confusing this resurrection with Jason's earlier returns. Jason had already survived or returned after previous apparent deaths, but Part VI is the installment that clearly establishes the lightning-powered resurrection and his zombie-like status.