Benjamin "Benji" Dunn is an Impossible Mission Force technician turned field agent and one of Ethan Hunt's main team mates.
Operation Rabbit's Foot
Benji, who was once a technician, aided Ethan Hunt during the events of his wife, Julia Mead's kidnapping. Ethan eventually rescues Julia with the aid of Dunn.
Ghost Protocol Incident
Benji was later promoted to a field agent and helped break Hunt out of a Russian prison. He aided Hunt on his next two missions to infiltrate the Kremlin and then to retrieve nuclear launch codes from Kurt Hendricks. During the attempt to bring a broadcasting station back online, he realized that William Brandt was taking too long and went after him, leaving Jane Carter to finish the job as she was too injured to go after Brandt. Dunn arrived in time to kill Wistrom as he fought Brandt, allowing Brandt to restore power to the station and Ethan to disable the nuclear missile. Dunn later happily accepted another mission from Ethan.
Rogue Nation Incident
After the IMF was shut down by CIA Director Alan Hunley, Benji found himself stuck behind a desk once more, attending weekly polygraphs to ensure that he was not secretly helping Ethan evade the CIA. After winning tickets to a performance of Turandot in Vienna, Benji made his way there only to realise that the tickets were a plot by Ethan to enlist his help in his search for Solomon Lane, the elusive leader of the Syndicate. After helping Ethan in Vienna, Benji insisted on staying, despite Ethan demanding him to leave for the sake of his safety, and the pair followed undercover MI6 agent Ilsa Faust to Casablanca, Morocco. This act added Benji to Hunley's hit list and he became wanted by the CIA. After the heist on the power plant, Benji was rendered unconscious by Ilsa so that she could steal the disc that Lane was after (fortunately, Benji had made a second copy of this information). Ethan and Benji chased after Ilsa, resulting in their car crashing and flipping repeatedly.
After the crash, they joined forces with Brandt and Luther, who had been chasing them down in an attempt to find them before the CIA did. The four of them tracked down Ilsa to London, cornering her in a train station where they found out that her copy of the disc had been wiped, resulting in Lane to take drastic measures. Lane then kidnapped Benji and held him for ransom. His demands: the disc for Benji's life. Lane strapped a bomb to Benji's chest and placed him in a busy restaurant on the Thames, the explosives on both a timer and pressure trigger to force Ethan's hand. Fortunately, Ethan managed to barter with Lane for Benji's life and Lane released Benji. Benji then helped Ethan and the others capture Lane.
- Mission: Impossible III (First appearance)