Disregarding politicians and people with obnoxious opinions, such as Jeremy Clarkson or Carol Malone, there are plenty of people I dislike for fairly irrational reasons, including :
Smug - Ian Hislop, Paul Hollywood, Dawn French, James Martin, Caroline Quentin and Ricky Gervais, the king of smugness.
Creepy - Stephen Fry, David Walliams, Laurence Fox (obnoxious opinions too.)
Generally irritating - Graham Norton, Sarah Millican, Frank Skinner. There's also a slimy man who makes a big thing about being a working class right wing comedian, but I can't remember his name.
Don't know how any could dislike Professor Brian Cox. Extremely clever and such a soothing voice. He should read bedtime stories.