King Cheops, also known as King Khufu (or King Ka-Hoo-Fu) was a man (either dognose or human, depending on the source) who later became an undead mummy, before eventually becoming a pure spirit and moving on to the afterlife.
An ancient Egyptian pharaoh, King Cheops was on friendly terms with the monarch of Garbabel, the Garbled One. At some point in his reign, he was also notable for giving an audience to the magician Dedi, who impressed him with hypnosis and tricks and manipulated the monarch into giving him a high rank in his court (kickstarting Egypt's reputation as a land of mystery and magic).
Ironically, a post-mortem Cheops ended up on the receiving end of genuine magic, as his spirit was trapped through dark magic within his mummified remains. Said mummy was, at some point, obtained by the High Priest of Garbabel, with Sarkus (the last and treacherous holder of the title, in the late 20th century) often using the reanimated Cheops as a henchman. In his mummy form, Cheops was frighteningly strong and resilient, but had little wits about him, and could only communicate in moans and groans.
In 1987, the spirit of the Garbled One was freed by Donald Duck from the Jar of Garbling. To the surprise of the cult that sought to reincarnate him, the Garbled One instead chose to move on. Spotting the undead Cheops, the ancient spirit effortlessly undid his bandages, revealing that only Cheops's ghost was left to hold them together, the body long worn away into dust. The freed, relieved Cheops and his old friend flew into the heavens as ethereal spirits, never to be seen again.
Behind the scenes
King Cheops first appeared in flashbacks in the 1957 story Mickey Mouse in Magic Land. He was featured more prominently (under the name "Khufu", a closer rendition of the original Egyptian than "Cheops", which is based on the Greek transliteration) in the iconic DuckTales episode Sphinx for the Memories; a somewhat similar mummy appears in the opening credits, though it is unknown if it is also Cheops/Khufu. Cheops is also obliquely mentioned in a Duck Avenger story, by way of the mention of a King Cheops Jr., presumed to be the son and heir of the more well-known King Cheops.
Naturally, Khufu was a genuine historical figure, who ruled over the Old Kingdom of Egypt around the 26th century B.C.E. and is most famous for building the Great Pyramid. Interestingly, the precise fate of Khufu's mummy is in fact unknown to real-world historians as of 2018, though it may well lie within his Pyramid.