Corwin was a hunter whom Bilbo Baggins met in Mirkwood. He and his men made a camp in Mirkwood. Though they were attacked by Spiders, Corwin was the only survivor as the spiders killed the rest of the camp including his brother. While searching for oil on Corwin's advice, Bilbo found a ring that once belonged to Corwin's brother. He gave Corwin this ring and then used the oil to burn down a thick spider web that was blocking his path.
He also participated in the Battle of the Five Armies. When he was attacked by goblins, Bilbo saved him. After that, he helps Bilbo to deliver the letter to Bard. After that, his fate is unknown.