King Ptolemy was the first king of the Ptolemaic Dynasty. Ptolemy was responsible for Serapis' rise to power.
When Alexander the Great died, Ptolemy the First took over Egypt. He discovered a statue of Serapis and brought it to Alexandria, ordering the Greek and Egyptian priests to do auguries and incantations. He made Serapis the main god and worshipped over all others. He decided that making him a major god, he wanted to become immortal too. He declared himself a god, but his magic backfired. After his death, his family was cursed for generations and grew weaker and weaker until Cleopatra committed suicide.
Ptolemy was briefly mentioned by Serapis when explaining how he came to power.