#1: S.A.S - Britain
The Special Air Service (S.A.S) is a special forces unit of the British Army that was created in 1941 by Colonel David Sterling during World War 2 for one purpose, to destroy the Nazi war machine. Today the unit undertakes a number of roles including covert reconnaissance, counter-terrorism, direct action and hostage rescue. The unit gained fame and recognition worldwide after its televised rescue of all but one of the hostages held during the 1980 Iranian Embassy siege. The SAS are without doubt the most highly trained unit in the world.
#2: Navy SEALS - USA
The United States Navy's Sea, Air, and Land Teams, commonly known as Navy SEALs are an American special forces that were created in 1962. The SEALs are trained to operate in all environments and their main functions are conducting small-unit maritime military operations that originate from, and return to, a river, ocean, swamp, delta, or coastline. Operations include gathering intelligence, destroying targets, and performing rescues.
#3: Spetsgruppa 'A' (Alpha Group) - Russia
Russian Special Purpose Forces or Spetsnaz was created by the Soviet KGB in 1974 and is a collective term for Russian units that are dedicated to counter-terrorism, paramilitary and covert operations both domestically and internationally. Alpha Group primarily prevents and responds to violent acts in public transportation and buildings.
#4: Shayeet 13 - Israel
Shayeet 13 was created in 1948 and is associated with the Israeli navy. This elite unit has taken part in every major Israeli operation since World War 2 conducting everything from hostage rescue and counter-terrorism to intelligence gathering and boarding. Their most notable operation was after the 1972 Munich Olympics when they were used to hunt down and eliminate those responsible for the attack on the Israeli athletes.
#5: Delta Force - USA
1st Special Forces Operational Detachment-Delta or Delta Force as they are more commonly known was created in 1977 as a result of high-profile terrorist operations. In addition to counter-terrorism operations this unit also take part in hostage rescue, raids, reconnaissance and less covert direct action operations. Delta Force is largely comprised of soldiers who have served in US special-forces like the Green Berets or Rangers.