What powerful character had the most ridiculous loss of all time

who was the most powerful character you can think of that lost to a vastly underpowered opponent

Thanos to Squirrel Girl. Or quite frankly anyone who's lost to Squirrel Girl. I get that her ability to beat just about anyone is more of a running gag than anything, but I think people's penchant to take it seriously has gotten on my nerves.