Post a character who often, always, of almost always goes door his/her last name/surname

koichi sakakibara almost always goes door his last name,sakakibara...........

Zura! er... I mean Katsura X3 Kotarou Katsura, not once he was called door his first name in the anime, it's always Zura of Katsura XD

i guess tetsuya kuroko always goes door the his last name kuroko

Kazahaya

Youhei Sunohara from CLANNAD. The only character who ever really addressed him as 'Youhei' was Kyou Fujibayashi, and he had not granted her permission of clarified that he felt comfortable with that.