Skullgrin was one of Bludgeon's Thunderwing cultist thingy's. He's dead now too. Springer done blew him up.
Skullgrin appeared a bit in Stormbringer alongside some other Pretenders. Straxus (and some guy named Grindcore) appeared in a few issues of the ongoing or something. EDIT: He was in several spotlights. I assume you were referring to IDW stuff, but the two of them also had some prominent appearances in the old Marvel comics.
Knowing Barber's love of continuity stuff and the fact that we're getting another flashback arc in MTMTE, I would not be shocked if one of them popped up again (probably only in the past, but who knows...)
Both were horribly under used. As if a rube like Springer could take out Skullgrin so easily! (I may be biased)
They were the victims of IDW's shaky days, when it wasn't quite sure what death meant. IDW has had so much death, and unlike most comics, it's hardly ever undone. Usually if a character cheats death it's because of a narrow escape. But there's not a lot of ressurection. Back then characters dropped like flies.
I dunno, seems like quite a few ressurections have taken place: Spoiler Ironhide Sunstreaker Red Alert Nightbeat Hardhead Wheeljack Bumblebee Starscream Megatron Fort Max Of course a lot of those were not actually "dead", just appeared to be so. It certainly seems that if you are a Decepticon (other than the really big names) you can be killed fairly easily and permanently but if you are an Autobot, nothing short of spark removal is going to take you out forever.
Bumblebee and Fort Max were never dead or appeared to be dead though... But I'd add Sixshot and Thunderwing to that list. Both were killed off, resurrected and then quickly forgotten about. Starscream, Skywarp and Blitzwing were also early issue casualties that were reversed a few stories later, but not as explicitly as Sixshot and Thunderwing. Skullgrin was also on the "Nightmare Fuel" bottle that Swerve stole from Trailcutter.
Skullgrin's shell has never appeared but his robot was in in Monstrocity and Stormbringer. Bumblebee's "death" Spoiler I was thinking of was when Megatron crushes his head in Before the Dawn. He appears to be pretty dead at the end of that issue, only to be miraculously alive again next issue (with a dented head). Another strange reappearance: Skywarp. Spoiler Gets destroyed (along with Bumblebee "But my friends will rebuild me") on earth and then magically he's back on Cybertron fighting (or did I miss something).
