Some false prophets in the Bible include Balaam and the prophets of Baal. The false prophets of Baal appear in the Old Testament in the book of 1 Kings.
One of the most notable cases involving false prophets in the Bible occurs when Elijah is pitted against the 450 prophets of Baal in Mount Carmel. Elijah and the false prophets undergo a contest, calling down fire from their gods to burn the offerings. Although the prophets of Baal call for fire, they don't succeed, but Elijah does. Another false prophet is Balaam, a diviner hired to curse Israel in the Old Testament book of Numbers. However, God forbids this.
The Bible warns often against false prophets and teachers, which include people who deceive others for their own ends and who pretend to be ministers of righteousness for gain. False prophets and teachers teach false gospels, which are religious truths that are watered down or changed to make everybody happy. Peter warns against these false prophets in 2 Peter, calling them adulterers and deceivers.
Paul also calls them deceitful, and he calls out a few false teachers in the New Testament, including Phygellus, Hermogenes, Demas and Diotrephes. Jesus warns against false teachers among the scribes and Pharisees during his time.