Most annoying nobles?

Which nobles were the biggest pain in the arses of the respective monarchs they served under? And were they justified in it or not? And were they successful?

The one in my head currently is Thomas, 2nd Earl of Lancaster.

As to whether he was justified in his opposition, I’d say that whilst Edward II did need someone to rein him in, Lancaster was not the one to do it. He himself was reckless and impulsive for choosing to execute Gaveston after a sham trial, proved to be petty by refusing to meet Edward for two years at Parliament, was very difficult to compromise with and not particularly good at governing the country. His execution, conspicuously similar to Gaveston’s, was probably the correct course.

A couple of other pain in the arses nobles were John de Vere, 13th Earl of Oxford and Roger Bigod, 5th Earl of Norfolk.