Saul (King)'s daughter Merab's husband.
1 Sam 18:19But at the time when Saul's daughter Merab should have been given to David, she was given to Adriel the Meholathite as a wife.
2 Sam 21:8So the king took the two sons of Saul, Armoni and Mephibosheth, whom Aiah's daughter Rizpah had borne to him, and the five sons of Adriel the son of Barzillai the Meholathite, whom he had fathered by Saul's daughter Merab.