"Cthulhu has also been spelled as Tulu, Clulu, Clooloo, Cthulu, Cthullu, C'thulhu, Cighulu, Cathulu, C'thlu, Kathulu, Kutulu, Kthulhu, Q’thulu, K'tulu, Kthulhut, Kutu, Kulhu, Kutunluu, Ktulu, Cathulu, Cuitiliú, Thu Thu" -Ripped shamelessly from the wiki page for Cthulhu.
The name has never been 100% set in stone as Lovecraft was quoted as saying it's his closest representation of the name of the star child as humans can't replicate the tongue of the outworlders.