Costas Georgiou, Cypriot-born British mercenary in the Angolan Civil War (born 1951)

Costas Georgiou, also known by his alias Colonel Callan, was a Greek Cypriot turned-mercenary who was executed in Angola following the Luanda Trial for activities during the civil war phase of the Angolan War of Independence.

A mercenary is a private individual who joins an armed conflict for personal profit, is otherwise an outsider to the conflict, and is not a member of any other official military. Mercenaries fight for money or other forms of payment rather than for political interests.

The Angolan Civil War was a civil war in Angola, beginning in 1975 and continuing, with interludes, until 2002. The war began immediately after Angola became independent from Portugal in November 1975. It was a power struggle between two former anti-colonial guerrilla movements, the communist People's Movement for the Liberation of Angola (MPLA) and the anti-communist National Union for the Total Independence of Angola (UNITA).

July 10 is the 191st day of the year in the Gregorian calendar; 174 days remain until the end of the year.