It is called the First Triumvirate. The members are Crassus, Pompey, and Caesar. The course of action of this First Triumvirate had no legitimate status, and its motivation was to solidify the political energy of the three and their supporters against the senatorial tip top.
The answer to your question is Triumvirate. Triumvirate is a group of three men holding power, in particular unofficial coalition of Julius Caesar, Pompey and Crasus. This was first Triumvirate which was created in 60BC. There was also a second Triumvirate which was formed by Antony, Lepidus and Octavian in 43BC.