Tomoyuki Oka (岡 倫之, Oka Tomoyuki, born June 12, 1991) is a Japanese professional wrestler trained by and signed to New Japan Pro-Wrestling (NJPW) where he is a two-time IWGP Tag Team Champion with United Empire teammate Jeff Cobb under the ring name Great-O-Khan (グレート-O-カーン, Gurēto-Ō-Kān).