Which king of Moab did Ehud kill with a double-edged sword?

Answer: Eglon

Ehud brought tribute to Eglon, claimed a secret message for him, then plunged his sword into the obese king's belly.

“And again they cried out to the LORD, and He raised up Ehud son of Gera, a left-handed Benjamite, as their deliverer. So they sent him with tribute to Eglon king of Moab.”— Judges 3:15 (BSB)