Leo Fitz was one of the S.H.I.E.L.D. field agents who formed part of Phil Coulson's team to investigate how the terrorist Abu Mussan got hold of an Uru sword. Fitz helped Heimdall (the owner of the Uru sword) break free from Mussan's terrorist group. When Heimdall revealed to have been possessed by an alien rock encrusted in his chest, Coulson ordered Fitz to get the Vision, so the android could sneak up on Heimdall and remove the alien rock.
After Heimdall was dispossessed from the influence of an alien rock, and Jemma Simmons recovered fragments of it, Fitz began investigating it on the Helicarrier. Some times later, Fitz and Agent Melinda May were appointed to protect Wiccan from Ethan Slaughter, who shot most of Earths most powerful sorcerers. With the help of Scarlet Witch, the S.H.I.E.L.D. agents were able to do so. Together with May and the Scarlet Witch, Fitz travelled to the Antarctica, where the team found out about Horguun, who produced the magic bullets with whom Slaughter gunned the sorcerers down. They were able to stop Horguun and his workers. Shortly before they left, Fitz turned out to be possessed by Dormammu's mindless plague and shot the Scarlet Witch. He was cured after his teammates managed to defeat Dormammu.
Some time later, Fitz was assigned by Coulson go undercover as a triple agent against the Department of Defense's General Strakovsky. One of his tasks as a double agent involved deliberately sending Agents May and Morse into a set-up wrong location when they were searching for the Quantum Drive, allowing John Walker and the U.S. Military to secure the Drive for themselves.
Even though S.H.I.E.L.D. managed to get the Quantum Drive back into their possession, they weren't able to identify the mole inside their ranks, prompting Director Maria Hill to hire outsider Elektra Natchios to investigate the team. However, Hill had previously destituted Coulson, the only person to know about Leo's true alleigance. Thus, he didn't have anybody within S.H.I.E.L.D. to fall back on, and he was quickly found out by Elektra. He escaped the airbase by using a teleportation device and joined former Agent Coulson. When Elektra and Coulson's former subordinates apprehended them, Fitz was able to flee with Quake in Lola.
After Maria Hill decided to cut Coulson loose, he resorted to Leo and Quake to bring General Strakovsky to justice. Fitz visited the General, and managed to get a confession out of him that he was planning to illegally sell weapons to Russia. Following Strakovsky's arrest, Fitz was reinstated as an agent together with Coulson and Quake.
- Leo Fitz is a Level 5 S.H.I.E.L.D. agent 
- Leo Fitz is a character originally created for the Marvel Cinematic Universe. He is modeled after his MCU counterpart's actor, Iain De Caestecker.
- 20 appearance(s) of Leopold Fitz (Earth-616)
- 3 minor appearance(s) of Leopold Fitz (Earth-616)
- 17 image(s) of Leopold Fitz (Earth-616)