Is ONE PIECE episode 368 filler?
Canon No, episode 368 of ONE PIECE is canon.
#368
The Silent Assault!! The Mysterious Visitor, Tyrant Kuma
足音なき襲来！！謎の訪問者・暴君くま
Aired 31 Aug 2008
Mochibayo compiled this list from MyAnimeList's labels, because MyAnimeList's episode data is not reaching us at the moment.