Alphys Hedge

The more I think about it, I think Bill Cipher might be my favorite antagonist of all time. He sets a clear reason for being killed: He has no redeemable qualities, he's completely psychotic, and I absolutely love that. While villains that are introduced to be reformed are nice, I think almost every show needs a completely irredeemable villain, something to actually work against. I think Gravity Falls seriously nailed that.

As much as I love Star Vs. and Steven Universe, I honestly think nothing will ever top Gravity Falls.