3 men who sacrificed their sons to false gods

Sacrificing children to false gods was common in the pagan nations of the anceint near east, and was copied by the Israelites. The Smaartians also engaged in this repulsive sin. Three individuals are identified as engaging in the practice as follows

A King of Moab

2 Kings 3:27 Then he took his firstborn son, who was to succeed him as king, and offered him as a sacrifice on the city wall. The fury against Israel was great; they withdrew and returned to their own land.

Ahaz

2 Kings 16:3 He followed the ways of the kings of Israel and even sacrificed his son in the fire, engaging in the detestable practices of the nations the LORD had driven out before the Israelites.

2 Chronicles 28:3 He burned sacrifices in the Valley of Ben Hinnom and sacrificed his children in the fire, engaging in the detestable practices of the nations the LORD had driven out before the Israelites.

Manasseh

2 Kings 21:6 He sacrificed his own son in the fire, practiced divination, sought omens, and consulted mediums and spiritists. He did much evil in the eyes of the LORD, arousing his anger.

2 Chronicles 33:6 He sacrificed his children in the fire in the Valley of Ben Hinnom, practiced divination and witchcraft, sought omens, and consulted mediums and spiritists. He did much evil in the eyes of the LORD, arousing his anger.

Also there is Jephthah in Judges, which is different, and Abraham, of course, in Genesis 22 but that is again quite a different story.