Balaam

All you ever needed to know about Balaam is right here in this song. 

He was a prophet of Yahweh in the time of Moses.  He was paid to curse Israel, but he only blessed Israel instead. (Numbers 22-24)  The text suggests, and later stories spell out, that Balaam taught Barak, the king of the Moabites, how to defeat the Israelites—to have his young women seduce the young men of Israel and convince them to worship other gods. (Numbers 31:13-18)  Balaam was eventually killed by the Israelite army. (Numbers 31:8).  In the Jude tradition, Balaam became a byword for a teacher of God who does so for personal profit (Jude 1:11; II Peter 2:15).

In Revelation, Balaam is a picture of a prophet who knows just enough truth to be dangerous and uses that knowledge to draw people into idolatry.  At the time of writing, there were people teaching Christians that it is okay to give into worshiping Caesar... add Christian excuse after.  "God will always forgive you after."  "You need to get along in the world."  "Sometimes a compromise is the best."