Malcolm Ceann Mor was a male anthropomorphic duck.
A son of Duncan I and the brother of Donald Bane, Malcolm Ceann Mor (meaning “Malcolm the Big-Headed”) led an uprising against usurper to the throne Macbeth and managed to capture and kill him at the siege of Castle McDuck in 1057. He reigned over Scotland until his death in 1090, upon which his son Duncan only briefly became King before being deposed by Malcolm's brother Donald.
Behind the scenes
Malcolm Ceann Mor is mentioned in the 1975 story The Famous Donalds. He is, of course, based on the historical King Malcolm III of Scotland, who was indeed nicknamed “Ceann Mòr”, although it is believed that "Head" is actually not to be interpreted literally but rather as in ‘head of state’, “Ceann Mòr" thus meaning "the Mighty Leader" rather than "the Big-Headed".