What was the name of Caesar's only son with Cleopatra?

Caesar’s only son with Cleopatra was Caesarion, formally named Ptolemy XV Caesar. He was born in Egypt in 47 BCE to Cleopatra VII and was presented by his mother as the biological son of Julius Caesar.

Caesarion spent part of his early childhood in Rome with Cleopatra, who had been Caesar’s guest after his Alexandrian campaign. After Caesar’s assassination in 44 BCE, Cleopatra returned to Egypt and made the young Caesarion co-ruler. He was pharaoh in name, while Cleopatra retained effective political control.

His parentage became politically explosive because Octavian, Caesar’s adopted son and heir under Roman law, was competing with Antony and Cleopatra. In 34 BCE, Antony publicly described Caesarion as Caesar’s true son and granted him grand royal titles. After Antony and Cleopatra’s defeat, Octavian captured Alexandria and ordered Caesarion’s execution in 30 BCE. Although ancient sources sometimes qualify his paternity as alleged, Caesarion is the standard historical answer to this question.