Sylar, the telekinetic villain / occasional anti-hero on NBC's Heroes, represents one of the most frustrating paradoxes on television.
On the one hand, he must die. The producers' inability to tell any story without it being inevitably hijacked by Sylar is the cancer killing the show, and the fact that his storylines either feel completely disconnected from or mesh uncomfortably with everyone else's, his constant stream of obvious fake deaths and exhaustingly predictable revivings, his haphazard, illogical lurching from evil to semi-good and back again, him losing and regaining his powers over and over, and the stagnant boredom of having one main villain for four seasons now make it clear: he's the worst character on the show, and he's gotta go.
On the other hand, he must never die. Zachary Quinto is the most entertaining actor on the show by a country mile, often the only one who seems alive onscreen, and Sylar is pretty much the only character who gets to cut loose and have some fun with his powers rather than being pickled in nonstop wall-to-wall angst. That, along with the fact that his scenes are without fail the most entertaining (if not only entertaining) scenes in any given episode, and every episode he's not in suffers for the loss, make it clear: he's the best character on the show, and he's gotta stay.
What's a showrunner to do? Well, other than bite the bullet and put Heroes out of its misery, I mean.