Cassius may refer to:
People Ancient world Cassius, an ancient Roman family name: see Cassia gens Gaius Cassius Longinus (died 42 BC), Roman senator and a leader of Julius Caesar's assassination Avidius Cassius (130–175), usurper Roman emperor Cassius Chaerea, 1st-century Roman army soldier and officer in the Praetorian Guard and assassin of Emperor Caligula Cassius Dio (c. AD 155 or 163/164–after 229), Roman historian Cassius Longinus (disambiguation) Cassius of Clermont (died c. 260), Roman senator and Christian martyr Cassius of Narni (died 558), Bishop of Narni
Modern world Cassius Clay (1942–2016), birth name of American boxer Muhammad Ali Cassius Marcellus Clay Sr. (1912–1989), father of the boxer Cassius Marcellus Clay (1810–1903), American abolitionist, nicknamed the "Lion of White Hall" Cassius Stanley (born 1999), American basketball player Cassius Turvey (2007–2022), Aboriginal Australian boy killed in Perth Cassius Winston (born 1998), American basketball player Cassius, pen-name of Michael Foot, British politician and writer Saint Cassius (musician), stage name of American musician Khalil Walton
Fictional characters Cassius au Bellona, in Pierce Brown's Red Rising series of novels Cassius Bright, in the video game The Legend of Heroes: Trails in the Sky Cassius Green, in the film Sorry to Bother You
Music Cassius (band), a French electronic music duo "Cassius" (song), a 2008 song by Foals "Cassius", a 2017 song on the album Crack-Up by Fleet Foxes
Other uses Cassius (crocodile), the world's largest captive crocodile Team Cassius, a competitor in the UK version of Robot Wars Cassius Chrome, a house robot in the UK version of Robot Wars
See also Kassius, a given name Kasius, a recurring character in season 5 of Agents of S.H.I.E.L.D.