Beleriphon
Totally Awesome Pirate Brain
One villain has a teleporter to get away, but I think that's it. No villains other then that are assumed to escape.
Only other one kind of like this is the mind flayer in Dragon Heist, during the sewer run before the plot really gets going. I think it probably better the mind flayer leaves, since that part of the adventure is gearing to first or second level characters.
Mind you, in that instance the creature isn't escaping, so much as leaving as soon as the players show up. And the area is setup so that there is no way for the characters to reach the mind flayer before it leaves. If they manage it some how, it just mind blasts them until it can leave.