Honestly, I’m vaguely tempted to offer Snowcone for this, since her many game overs mean she can be depicted dying horribly in a multitude of ways without it actually going against canon.
Alternately, Wawa, who will canonically(?) be drowned by Snowcone so if he dies to robots that’s pretty clearly non-canon. Wawa is also very good at tormenting other fluffies and killing foals though, if you’d rather take that route. Both are in my OC list (#3 and #4 respectively).