Cissa () was part of an Anglo-Saxon invasion force that landed in three ships at a place called Cymensora in AD 477. The invasion was led by Cissa's father Ælle and included his two brothers. They are said to have fought against the local Britons. Their conquest of what became Sussex, England continued when they fought a battle on the margins of Mecredesburne in 485 and Pevensey in 491 where they are said to have slaughtered their opponents to the last man.