Revelation: The “dragon” represents Satan as does the “beast”. The sea was thought of as Satan’s domain. After all, humans can’t live in the sea. The crowns and horns represent power. The animals mentioned: a leopard (i.e., Greece); a Bear (Medo-Persian Empire); a lion (Babylon), these all converge at one point or another to destroy Israel. It is important not to assign any of these symbols to people we see today on the world stage. These are roles which change actors as needed.
Gospel: Luke 12:13-31
New Testament: Revelation 13:1-10
Old Testament: Genesis 7:13-24