Brother Ahab is a character who makes a one-time appearance in the Season 2 episode titled "Dambreakers".
Brother Ahab is the cover name used by one of the terrorists led by Johann Rector. His group had taken a "back to nature" religious community hostage and were using it as a cover to mount an operation to blow a hydroelectric dam.
When Hawke and reporter Kelly Dayton arrive at the community to do an interview, Ahab does not welcome their presence. During the night he patrols the grounds and finds Hawke wandering outside. He accuses Hawke of "snooping around" and tells him that if he has nothing much to do, why did he not just leave the place. The encounter gets tense but Rector (whose cover name is Brother Jebediah) intervenes and takes Ahab away, admonishing him to exercise more patience (since Ahab's violent attitude might well their cover)
Later the gloves come off and Hawke and Kelly are taken into custody by Rector and Hana. They are locked up in a room and Ahab is assigned to guard them. Hawke gets Kelly to undress to her underwear to distract Ahab and jumps him, knocking him out and tying him up. Hawke and Kelly then make their escape.
Ahab is later released by Hana but his ultimate fate is not known. He might have been on the B-25 like some of the others in the gang, in which case he would have been killed when it is shot down by Airwolf.