Coulson was seemingly killed by Loki in The Avengers when Coulson tries to stop Loki from ejecting Thor from the Helicarrier. Coulson's apparent death was the trigger which finally united the Avengers.
After the events of the Avengers, Coulson assembles a small team of agents, consisting of Melinda May, Grant Ward, Leo Fitz, Jemma Simmons and Skye, to investigate the new, the strange and the unknown. Coulson and Maria Hill later explained to Agent Ward that Fury "faked Coulson's death to motivate the Avengers".
Phil Coulson is played by Clark Gregg.