I'm going to include characters whose presence irks me, but not including those that meet the following criteria:
-Keep turning up and keep getting back up, but are still engaging on some level
-Keep hanging around, but are detestable in a good way (your Ramsay Snows/Joffrey Lannisters of fiction)
So with that said:
-Travis (Blake's 7): I don't dislike Travis per se, and he at least has an arc of sorts over the first two seasons he's in, but it's an arc that requires the protagonists to keep letting him go, when they could just kill him. It really stretches credulity in a setting that's already stretching credulity.
-Seymour (Final Fantasy X): You keep killing him and he keeps coming back, because Yuna squanders every chance she has to banish him right up until the end. He's at least a functional adversary that ties in with the context, but he's not so good a villain that him staying around is worth the protagonists holding the idiot ball.
-Morgana (Merlin): Sort of. She's kind of squandered in that towards the end of the series, repetition had really set in, and her death is so anti-climactic, in what was an absolutely terrible conclusion to the series. I think my listing her here is more her being a victim of circumstance rather than me disliking her character, but I do feel Morgana overstayed her welcome.
-Cromartie (Terminator: Sarah Connor Chronicles): Have I ever said how much I loathe this show? Well, if I haven't, now you know. And this bozo is just one of the many reasons. That's right, in T:SCC, every T-888 in existence has been sent back to the past (because this level of time travel is a thing now), and gets taken out in minutes (because that's also a thing), but this jackass, who loses his head and flesh, and still goes through a time displacement sphere, sticks around for the entire first season (yay...), before finally being downed in season 2 by SMGs because...SMGs can take down a Terminator now?
Yeah, screw him.
-The Master (Doctor Who): Sort of - Doctor Who has kept bringing back villains, but the Master really feels out of place, since the last we saw him was at the end of Ten's run (good closure on multiple levels), but then game back as "Missy." Which is a shame, because on one hand, as a character on her own, "Missy" is quite enjoyable, but on the other, it feels out of sync with the Master in the past, and unfortunately introduced the precedent of time lords switching genders. If Missy was a completely separate character I'd love her for it, but as it is now, the Master is on this list.
-Gabriel (The Walking Dead): I haven't watched beyond season 5 of TWD, and with season 5 being my least favorite of those seasons, I probably won't get to season 6 in the near future. But, Gabriel. In concept, he's fine - unprepared for the harsh nature of the world, ignorant of how bad things are, and doesn't rise to the occassion. That's fine, not everyone could adapt. Still, by the end of season 5, Gabriel has established himself as a liar, careless (leaves the gate open), a coward, and an emotional sadist (e.g. the Sasha scene). Characters like The Governor fit into "Magnificent Bastard" territory. Gabriel, at least in my experience, is more in the "hurry up and die you twat" territory.
Edit: Oh, and:
McMarbles said:
Malcolm Merlynn officially hit this point back in Arrow season 3. And he's STILL around.
Ugh. This.
Season 3 was the last Arrow season I watched, and how Merlyn operated was part of it. I'm fine with him surviving season 1. What's less palatable is that everyone seems to give him a free pass for increasingly convoluted reasons. Yes, he's Thea's father. He's also a man who used Thea to kill Sarah, dragged them into a conflict with the League of Shadows, blackmailed Moira, and used a device that killed hundreds of people. And the protagonists are apparently fine with all this.
I'd be fine with Malcolm surviving if it wasn't for the fact that his survival hinges on Ollie and co. holding the idiot ball.