One theory is that Christopher Columbus served under the French corsair Guillaume Casenove Coulon and took this as his surname. Then at a later date airbrushed his past, in order to hide his piracy. There is no strong evidence for this.
It appears more probable that in 1476 Columbus was on a Genoese vessel in a convoy bound for Lisbon. The Spinola and Di Negro families had organized a trading venture to England. Five vessels sailed from Genoa, passed through the Strait of Gibraltar, and entered the Atlantic. Near Europe's extreme southwest point at Cape St. Vincent, they were attacked by French pirates cmmanded by a French corsair called Coulon, Colombo, or Colomb.
In the bitter battle, ships from both sides were sunk, including the one the Genoese agent was on. Although many drowned, Columbus reached shore, near Lagos in Portugal. Soon the young Columbus made his way to Lisbon. Here he took up residence and soon married.
The connection to royalty is demonstrated by the writings of Ferdinand and Las Casas, who quotes Columbus as saying that "[I] sailed with my kinsman, Colon the Younger, the Greek corsair"[pirate]. Colon the Younger was a member of the Palaeologi. His name was George Palaeologus Disipatos, and was also known as "George le Grec." He turned corsair after the fall of Constantinople, and fought the Turks on the sea after they'd conquered the Byzantine Empire. Ferdinand's book quotes a passage from a letter his father wrote to the nurse of Don Juan of Castile: "I am not the first Admiral of my family. Let them call me, then, by what name they will, for after all, David, the wisest of kings, tended sheep and was later made king of Jerusalem, and I am the servant of Him who raised David to that high estate."
Christopher Columbus - discoverer of America