Throughout the book of Revelation, He who sits on the throne is not Jesus, but rather the God and Father of Jesus. -- Revelation 1:4; 3:12; 4:3-6,9,10; 5:1,6,7,11,13; 6:16; 7:10; 20:5; 22:1.
Jesus (pictured by the lamb that was slain) is distinguished from He who is sitting on the throne in the following verses: Revelation 1:4,5; 5:6,7,13; 6:16; 7:9,10; 22:1.