Alphonso "Mack" Mackenzie is the director of the post-Coulson S.H.I.E.L.D.. He was previously the official mechanic for the reformed S.H.I.E.L.D. under Director Phil Coulson. He spent most of his time working on their plane, the Bus.
Once Skye and Trip returned with a quinjet with cloaking abilities, Coulson had Mack go over the plane's specs so he could reverse-engineer the cloaking technology, a task Mack was ultimately successful in as Coulson was able to demonstrate his "arsenal" of cloaked planes to Brigadier General Glenn Talbot. Later, Mack helped Leo Fitz develop a device that could stop Carl Creel, a Hydra assassin that could absorb any substance into his body and transform the molecules of his body into that substance. Fitz, who was brain damaged from almost drowning, had trouble conveying his ideas to his subordinates, and would often give in to outbursts of rage. Mack was able to calm Fitz down, and the two of them started to bond over their work. They found a device Fitz came up with in the past that would counter Creel's abilities.
While on a mission to Puerto Rico to investigate a mysterious city, Mack was sent down into a cavern possibly containing the city to repair D.W.A.R.F. robots sent by Fitz. Once he reached the bottom, Mack activated a design in the cavern floor that paralyzed his hand with immense pain. Once the rest of the team pulled him back up, Mack began attacking them. After nearly killing Bobbi Morse, Director Coulson fired rounds from an I.C.E.R. at him to no effect. Once he dropped Morse, Mack turned his attention on Coulson, and Fitz pointed a gun at him. Although Fitz was hesitant to fire, it gave Agent Morse the opportunity to sneak up behind him and touch the electrified ends of her staves to his neck. Mack convulsed and fell back into the cavern. Coulson ordered the opening be closed, and assured his team that Mack was gone.
When Raina had entered the city, she was scared to see Mack standing still in front of her. Realizing he had changed, she asked him to guide her to the temple, which he did immediately. When Raina was already inside the temple and Skye was arriving, she found Mack as well and tried to get him to come with her, thinking he wasn't being controlled. Upon realizing he was staying still, she entered the temple to follow Raina. Coulson got inside the city soon afterwards, and when Mack noticed his presence, he attacked Coulson, since he was not worthy of entering the temple. The moment the Diviner released mysterious mists inside the temple, Mack was released from the city's control. When Skye's powers created an earthquake, Mack escaped the city with Coulson. 
Unbeknownst to their friends, Mack and Bobbi were secretly working for a splinter organization also going by the name S.H.I.E.L.D. and were plotting to steal Coulson's Toolbox. However, when Mack mistakenly mentioned "real backup" during the fight with Vin-Tak, Hunter later confronted him, which forced Mack to abduct him and bring him to the other S.H.I.E.L.D.
Powers and Abilities
Skilled mechanic, experienced in melee combat and general espionage
- Henry Simmons portrayed Alphonso "Mack" Mackenzie in every episode of season 2 of Marvel's Agents of S.H.I.E.L.D. before being promoted to series regular for the third season. The only episode Mack does not appear in is "4,722 Hours".
- Mack is covered as an insurance agent. Though not outright stated, his brother describes him as "working for the lady with funny hair" suggesting his cover is with Progressive; his brother also routinely mistakes him for being "the gecko's sidekick," a further reference to Geico.
- 112 appearance(s) of Alphonso Mackenzie (Earth-199999)
- 1 minor appearance(s) of Alphonso Mackenzie (Earth-199999)
- 3 mention(s) of Alphonso Mackenzie (Earth-199999)
- 63 image(s) of Alphonso Mackenzie (Earth-199999)
- 6 quotation(s) by or about Alphonso Mackenzie (Earth-199999)
- 1 item(s) used/owned by Alphonso Mackenzie (Earth-199999)