The Sciritae, Sacred Band of Thebes, and Macedonian Hetairoi were some of the top special forces in ancient Greece, and they were renowned for their valor and deadly combat prowess. 

Ancient Greece had several special forces that were known for their bravery and fighting skills. These elite soldiers were some of the most dangerous and lethal powers of their time. The Sciritae, a mountainous people of Laconia who were subject to Sparta, played a pivotal role in battles and were considered elite soldiers. The Sacred Band of Thebes was a legendary special force made up exclusively of 150 pairs of friends who fought as a single battlefield unit. The Macedonian Hetairoi, an unbeatable special force, was a body of elite horsemen who fought closest to the king, Alexander the Great. They fulfilled the role of both royal household guard and elite mounted shock-troops of the Macedonian army. 

Source: https://greekreporter.com/2023/04/05/special-forces-ancient-greece/