Caius
In Latin, Caius is an archaic spelling of the Latin praenomen Gaius, pronounced /ga:ius/. In early Latin, the letter C was used for both /g/ and /k/; and the names Gaius and Gnaeus were spelt Caius and Cnaius and continued to be so in inscriptions, after the letter G was introduced, and C was confined to the /k/ sound. Notably, the name of Gaius Iulius Caesar is abbreviated CIC.
In English, Caius is a latinized spelling of the last name of John Keys of Gonville and Caius College, Cambridge.
Caius may refer to:
People
Given name
Ancient world
- Pope Caius (died 296), Bishop of Rome and martyr
 - Caius (bishop of Milan), bishop of Milan in the early 3rd-century, saint
 - Caius (presbyter), early 3rd century Christian writer
 - Caius Largennius (died c. 50), Roman legionary
 
Modern era
- Caius of Korea (1571–1624), Catholic missionary, one of the Martyrs of Japan
 - Caius Brediceanu (1879–1953), Romanian politician and diplomat
 - Caius Gabriel Cibber (1630–1700), Danish sculptor
 - Caius Iacob (1912–1992), Romanian mathematician and politician
 - Caius Lungu (1989–2025), Romanian footballer
 - Caius Novac (1821–?), Romanian footballer
 - Caius Welcker (1885–1939), Dutch footballer
 
Surname
- Jean Ferdinand Caius (1877–1944), French botanist and naturalist who worked in India
 - John Caius the Elder (fl. 1480), English poet
 - John Caius (1510–1573), English physician and second founder of Gonville and Caius College, Cambridge
 - Thomas Caius (died 1572), English academic and administrator, Fellow and Master of University College, Oxford
 
Fictional characters
In Shakespeare's plays
- Caius, in the play King Lear, the name that the Earl of Kent takes when in disguise
 - Caius, the protagonist in Coriolanus
 - Caius Lucius, Roman ambassador and later general in Cymbeline
 - Doctor Caius, a French doctor in The Merry Wives of Windsor
 - Caius, a casual nomer used in Camus’ play “Caligula” to refer to the tyrannical emperor of the same name.
 
Other
- Caius, in Sir John in Love, a 1929 English opera by Ralph Vaughan Williams, based on Shakespeare's The Merry Wives of Windsor
 - Caius, in the book The Skystone by Jack Whyte
 - Caius, in the Twilight series by Stephenie Meyer
 - Caius Ballad, the main antagonist in the video game Final Fantasy XIII-2
 - Caius Cosades, Grand Spymaster of the Blades in the video game The Elder Scrolls III: Morrowind
 - Caius, in the 1960 film Spartacus, played by John Hoyt
 - Caius Lao Vistaille, one of the protagonists in the manga (and later anime based on it) The Titan's Bride
 - Caius Qualls, the main protagonist of the video game Tales of the Tempest
 
See also
- Caius Choirbook, an illuminated choirbook
 - Caio (disambiguation)
 - Cayo (disambiguation)
 - Cai (name)