1. Victor Clemente
John Leguizamo's antagonistic physician is an improbable character from the get go thanks to his ridiculous posing as a patient. This time-wasting nonsense doesn't make him likeable or eccentric so much as plain annoying, a sentiment echoed by the leading characters fans actually were invested in.
It only gets worse from there as he becomes an increasingly unhinged rival to fan favourite Luka Kovač. Clemente's dreadful ex-girlfriend eats up more valuable screen time with an ill-fitting subplot regarding her psychotic police officer husband that'll leave many wondering why they watched this show to begin with. The story arc of Clemente gradually descending into madness is arguably the worst in the whole show. Hammily acted and scatter shot in its development, Clemente's fall from grace isn't gripping car crash TV as was intended. Instead, it is simply change the channel TV, a creative decision that derailed the entirety of season 12 before it was done.
Of the many attempts at a villainous resident, Clemente takes the cake as the worst. His distasteful nervous breakdown plot includes laughably poor moments like relieving himself in public and vandalism. One has to wonder what Leguizamo thought of the material they were handing him...