[@Kazemitsu] Well, let's see.  I know all of this isn't involved in our campaign specifically, but...we've had Ridley, Young Ridley, Clone Ridley, Meta Ridley, Omega Ridley, Cyber-Ridley, Ridley-X...  Ridley never stays dead, if anything else.  Neither does Phantoon, since he's a multi-dimensional being with many bodies.  And I think Mother Brain has multiple nodes, but I'll need confirmation on that.