Who he is: Alphonso Mackenzie, a.k.a. Mack
His power: No superpowers, but Mack is a trained S.H.I.E.L.D. agent—not as skilled in hand-to-hand combat as some of his colleagues (he has an unfortunate tendency to get knocked out a lot), but an expert in weaponry. His biggest assets are his skills as an engineer.
His story: Prior to his first appearance on Agents Of S.H.I.E.L.D., Mack left his family to join S.H.I.E.L.D. in 2002, working as chief engineer aboard one of the division’s aircraft carriers. He worked missions, including one with Bobbi Morse in Dubai, where he first met Lance Hunter. After the events of Captain America: The Winter Soldier, Mack (along with Bobbi) was tasked by acting S.H.I.E.L.D. head Robert Gonzales with infiltrating the rival faction of S.H.I.E.L.D. led by Phil Coulson. Eventually, the two groups joined together, with Mack transferring his loyalties to Coulson as head of S.H.I.E.L.D. He became a fast friend of Leo Fitz, and spends as much time in engineering as working missions. However, he took over as acting head of S.H.I.E.L.D. when Coulson left to try and rescue Fitz from Grant Ward. He was partners for a time with Daisy Johnson, and tried to bring her in when she was possessed by the Inhuman entity called Hive.
Mack became partners with Coulson after the latter was demoted from acting head of S.H.I.E.L.D., and they helped locate Daisy and return her to the team following her vigilante partnering with Ghost Rider. Unfortunately, soon after that Mack was captured by the cyborg AI Aida and unknowingly placed inside a VR program called the Framework.
Played by: Henry Simmons
Currently, Mack is: An active agent of S.H.I.E.L.D., but trapped inside a simulated reality.
Where will we see him next? Season four of Marvel’s Agents Of S.H.I.E.L.D., which began in September 2016.