Phil Coulson is a former Director of S.H.I.E.L.D. Prior to retiring, he was Nick Fury's right-hand man, serving on multiple projects and experiments, one of them being the Avengers Initiative. During the Attack on the Helicarrier, he was killed by Loki. His death gave the Avengers the push they needed. After the Chitauri Invasion, he was sent to Guest House by Nick Fury in order to resurrect him.