Tomoyuki Oka (岡 倫之 Oka Tomoyuki, born June 12, 1991) is a Japanese professional wrestler signed to New Japan Pro-Wrestling (NJPW), where he currently performs under the ring name Great-O-Khan (グレート-O-カーン Gurēto-O-Kan).
Oka made his debut for NJPW on January 3, 2017, and worked as a "Young Lion" over the following two years. In June 2018, Oka renamed "(The) Great O-Kharn", was sent to the British Revolution Pro Wrestling (RevPro) promotion to further his wrestling training and gain internation