pantomime villain

noun2

1. •
   (UK) A character archetype in pantomime entertainment.

   • In contrast, the best of the Pantomime villains are even entitled to misbehave, overact, and be disdainful of the audience. — 2020
2. •
   (UK, figurative) A person who has become a designated villain, often seen as cartoonishly villainous; someone people "love to hate".

   • The 'pantomime villain' he was labelled by the BBC commentary team, Abrial collected his medal [...] to a chorus of boos from those inside the Manchester Centre. — 2022