As far as people coming back after death in a TTRPG, don't overlook the benefits of bait and switch.
For an RCR campaign set in the Dark Times, I had my PCs facing a recurring nemesis in the form of a humanoid crime lord (not too unlike Dryden Vos in mannerisms) that no matter how the PCs thought they put an end to the guy, he kept coming back; it got to the point that the PCs were convinced the guy's middle name was Kenny. They had all sorts of speculations as to how the guy was doing it, especially after a few instances of them seeing the body.
His trick? Vat-grown clones that were in effect remotely controlled by a Columi in a sort of double-blind. The PCs never twigged in because they always made sure the crime lord's head was so thoroughly destroyed that any electronic/metallic bits were just written off as being cybernetic implants, which never aroused suspicion as the guy had an obvious implant that from all they could tell operated much like a hands-free comlink that allowed him to download/upload data into his brain.
Another instance was a d6 teen Jedi campaign set a few decades after RotJ and largely ignoring the EU published after the Thrawn Trilogy apart from a few choice bits, with the nemesis being a powerful Dark Jedi from the days of the Empire who after each dramatic fight would come back from the dead. Rather than it being Palps' trick from Dark Empire of shuffling his spirit into new imperfect clones that rapidly withered away, it was clones, but the BBEG's personality was essentially downloaded into the new body, which accounted for gaps in memory that the PCs just wrote off as being a side effect of denying death and forcibly keeping his spirit in the physical realm, especially as the guy merely shrugged off such gaps as no big deal.