Many actors do conventions. Devon Murray, Warwick Davis, Mike Edmonds (he's not credited but was a Goblin), Rusty Goeff, Ray Griffiths (same thing, goblins with no credit), John Hurt is at a convention now (NEVER thought I'd see that one... now that would be a great one to get!), Matthew Lewis, Harry Melling, Katie Purvis (uncredited Goblin), Chris Rankin, Adrian Rawlings, Kiran Shah (Uncredited Goblin), Danielle Tabor, Will Theakson, Jamie Waylett, Luke Youngblood, Christian Coulson, Emily Dale, Alfie Enoch, I THINK Shirley Henderson did on (or was supposed to), Toby Jones, Hugh Mitchell, Natalie Tena (oh add her to my list of possibles), Stanilav Ianeski (Krum), katie Leung, Christian Simpson, Tolger Safer, Ian Whyte, Afshan Azad, Hero Tiffin-Fiennes and a couple others have ALL done conventions.
Add me another two to my desire to meet list: Timothy Spall and Brendon Gleeson. Great parts! Great actors...
If anyone is interested, I am a collector (I do not sell anything) and not sure the rules of posting websites, but view my collection of autographs for Harry Potter (Possibly the largest or near largest anywhere). starwarsautographcollecting.com