Meaning A boy's name of Celtic origin, it means "From Arthurian legend." Origin of Cassivellaunus Celtic , Irish +-100%Zoom level changed to 1 Popular Middle Names Pronunciation 🔊 Listen Cassivellaunus Similar Names Caswallan Gwalchmai Guiomar Perce Cian Fergus Annan Artek Atre Arto Year by Year Popularity of Cassivellaunus