Looking back it was kind of obvious that Coulson was going to die. It was too early to kill off one of the big players and the death of lesser-know characters like Maria Hill or even Hawkeye would not have had the same impact. So Joss Whedon chose to kill off the the most likeable man in the entire Marvel Cinematic Universe instead. A character so popular, Phil Coulson's appearances on film eventually led to his arrival in the comics. But he would not make it past phase 1 alive. Loki skewing him with his spear was shocking, adding to his villainy and acting as a catalyst for Captain America, Iron Man et all to 'avenge' Coulson. But in true David versus Goliath fashion, Coulson got the final say, blasting Loki with a bloody big gun before giving his last breath. His resurrection in the TV series Agents of SHIELD added a layer of mystery to the show and led to a shocking, brutal revelation that in turn fuelled the alien city / Inhuman plot of season two. But it was his death scene in The Avengers that was the most memorable moment in Coulson's history.