Adil Akyuz was Arthur's Turkish pen pal, as seen in the Arthur episode Dear Adil. Later Arthur received a letter from Adil saying he was coming to visit, but actually Adil and his father were scheming to blow up Arthur's house and family. After a heated brawl, the bomb was deactivated by Kate Read (Adil Akyuz, Master of Terrorism). Adil is probably in jail now.
In Elwood, Adil has a unibrow and wears a turban. He is always either angry or somber.