Corinthia VII was an M-Class planet visited by the USS Enterprise sometime after 2254. Though initially believed to be devoid of any advanced life forms, a landing party discovered huge subterranean creatures on the planet, one of which killed landing party member Ensign Williams. (TOS - Strange New Worlds I short story: "A Private Anecdote")

planets visited by the USS Enterprise (NCC-1701) (2243-2264)
Robert April's command (2243-2251)	Earth • Romulan planetoid • Tarsus IV • Faramond
Christopher Pike's command (2251-2264)	Earth • GS391 • Areta • Magefferus III • Pharos siteworld • Rigel VII • Talos IV • Darien 224 • Prairie • Neyda Prime • Liria • Jubal • Theta Kalyb • Algol II • Temazi • Corinthia VII • Eridios