Taskforce 141 is the name of a multinational special forces group under the command of Lt.Gen.Shepherd. It's recruits come from multiple special forces units around the world including the S.A.S, 75th Ranger Regiment and Canadian Special Operations Regiment.
In the game, task force 141 was a multi-national task force that was formed to hunt down Makarov and it was compromised mainly from SOF soldiers. The only real life equivalent is Task Force 88 (anti-terrorist unit) , an anti-terrorist outfit that hunted down high value targets and either captured them or killed them.