Our "main" Vilgax from the original continuity has an unknown fate, he's just kinda floating in space and the original continuity ended prior to him coming back.
Vilgax from the Reboot is, of course, alive, with a sort of Two-Face scarring happening to him.
Vilgax from the original Ben 10K episode is frozen in what I assume was once a public pool. He was almost dead prior to this however, given the state we see him in before Animo revived him, caused by the events of Goodbye and Good Riddance.
Vilgax from the Gwen 10 universe I believe is dead.