One of the biggest surprises about the upcoming sixth season of Agents of S.H.I.E.L.D. is the inclusion of a mysterious, malevolent doppelgänger of the series lead Phil Coulson.

Last seen in the final moments of the Season 5 finale, Coulson was about to succumb to the mortal wounds he suffered from Loki in The Avengers. He ultimately decided to spend his final days relaxing in Tahiti with Agent Melinda May. However, the first trailer for Season 6 revealed Gregg's return as a new character who looks identical to the late S.H.I.E.L.D. operative.

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"There’s some strange anomaly happening that feels like a very threatening rupture every time it occurs and there are these people, these humanoid people who show up in the footage and one of them looks a lot like Coulson," Gregg explained to io9. "He’s bad, he’s dangerous, and terrifying. He’s a different person and it’s difficult for everyone to cope with, but especially Agent May and Daisy.”

With a new danger wearing a very familiar face, the titular agents of S.H.I.E.L.D. may be facing their most personal threat yet.

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Marvel's Agents of S.H.I.E.L.D. is set to return to ABC in May with 13 new episodes. The series stars Ming-Na Wen, Chloe Bennet, Henry Simmons, Iain De Caestecker, Natalia Cordova-Buckley, Elizabeth Henstridge and Clark Gregg.