Trek is full of iconic and much-loved characters, but are there any out there that you just don't like? This isn't about the characters lots of people dislike (Wesley, Neelix, etc).
Please don't let this descend into petty name-calling and snarky comments, after all it is people's own tastes--there are no right or wrong answers.
Personally, I have three:
The Doctor - I found him obnoxious and pompous, who only got worse as the series went on.
Seven of Nine - For me she killed Voyager, it should have just been called the Seven of Nine Show.
James T. Kirk - He has always come across to me as sleazy (here at home we'd call him "sleekit") and arrogant.