Hennessey is a fisherman who appears in "A Fish out of Water".
While Peter Griffin had his job as a fisherman, Hennessey, tried to stop Peter fishing on the same spot as him, by sending him to a Bar Mitzvah. This resulted in Peter unintentionally running over Mordecai, the Dancing Yiddish Clown. He also used a sign at Griffin's fish stand to tell people that Peter had sex with the fish he catches. He also believed that Griffin could not defeat Daggermouth, but challenged him to it in hopes he would fail.
He was voiced by Michael Chiklis.