"He [Peeves] wanted to attend the feast - well, it's quite out of the question, you know what he's like, utterly uncivilised, can't see a plate of food without throwing it. We held a ghosts' council - the Fat Friar was all for giving him the chance - but most wisely, in my opinion, the Bloody Baron put his foot down." --Nearly Headless Nick (GF12)
The ghosts’ council at Hogwarts is a group of ghosts including the House ghosts. They vote on matters that concern them.
It was held in 1994 to vote on whether or not Peeves was allowed to attend the start of term feast. The Fat Friar wanted to give Peeves a chance, but the Bloody Baron refused to allow it (GF12).