Super Troll !!

I have an unusual problem. I befriended a man on facebook a couple of months ago who was at that time just a bit of a joker. It turns out now that he is a troll. He delights in suddenly changing his happy go lucky attitude to an abusive one. He also delights in trying to cultivate the idea that im trying it on with my female facebook friends. Of course he gets great mileage out of these jaunts, but eventually people get tired of the joke and it wears thin. I never know who he has been winding up on my wall when I log on in a morning. I have tried to block him but his name is not recognized by facebook and I unfriended him a few days ago, and I unfriended him again this morning !! Ive blocked plenty of people before, but none have been unblockable, they may have had multiple accounts but I rooted them out eventually. I don't know what to do next. Maybe report this to facebook if it continues ?