Hiroki (裕樹, born March 29, 1968) is a Japanese seiyū (voice actor), theater actor and producer from Aichi Prefecture. His former stage name was Hiroki Ushiyama (written as 牛山 裕樹, 牛山 祐樹, 牛山 博喜). He currently belongs to Nexeed. He previously belonged to Ask Management. He started acting as an actor at the age of 41.