I wish I had a camera over the years. Never found a big snake, but a few cooked garden snakes, and two (2) cats on two occasions in 4160 volt switchgear.
They got in but never got out. One was re-fried when the maintenance guy re-energized the main not knowing the creature was on the buss. Nice!
Another that comes to mind was a groundhog that snuggled up in the primary ide of a padmount transformer. Got a call for a 'burning smell' in the office bldg. Followed my nose to the 4" UG conduits where it was wafting in from!
That snake wouldn't have to bite me. Just the sight of that thing would be enough to finish me off.
I remember seeing one of those poison ropes one time when I opened a safety switch to confirm that it had operated (at the scene of a house fire). The %#(#^* thing scared me so badly that I slammed the cover shut - decapitated it as he started poking his head out.
Another case for making sure all your KO's are closed, I guess. Probably not what the NEC had in mind though...