The Ultimates is a fictional superhero team appearing in American comic books published by Marvel Comics and created by writer Mark Millar and artist Bryan Hitch, which first started publication from The Ultimates #1 (cover date March 2002), as part of the company's Ultimate Marvel imprint. The series is a modernized re-imagining of Marvel's long-running Avengers comic-book franchise, centering around a task-force of super-humans and special agents organized by the U.S. government to combat growing threats to the world. The tale chronicles their progress as they bond and slowly learn to work together, despite their differing natures and personalities.

The first volume of the Ultimates, written by Millar and illustrated by Hitch, was published in limited series format and ran for thirteen issues with production delays from January 30, 2002 until March 31, 2004. Hitch described the alternative-reality reimagining as one where, "You have to approach it as though nothing has happened before and tell the story fresh from the start.... We had to get to the core of who these people were and build outwards, so Cap [Captain America] was a soldier, Thor is either a nut case or a messiah ... Banner [the Hulk] an insecure genius, and [superspy Nick] Fury the king of cool".

A second series, also by Millar and Hitch, was released as Ultimates 2 and ran 13 issues from Dec. 2004 to May 2007. The series had originally been slated for April 2004, but was resolicited to stockpile enough issues for a monthly release. It ran into similar production delays, however, due to Millar's struggles with Crohn's Disease and involvement writing Civil War, as well as the artists' need to keep busy with other work in the meantime.

In a 2004 interview, Millar outlined the difference between the Ultimates and the Avengers: "The idea behind The Avengers is that the Marvel Universe's biggest players all get together and fight all the biggest supervillains they can't defeat individually, whereas Ultimates 2 is an exploration of what happens when a bunch of ordinary people are turned into super-soldiers and being groomed to fight the real-life war on terror."

This was followed by the one-shot Ultimate Saga (Nov. 2007), a condensed retelling, by writers C. B. Cebulski and Mindy Owens and artist Travis Charest, of the events of Ultimates and Ultimates 2. A third series, Ultimates 3 (Dec 2007 – Sept 2008) was written by Jeph Loeb and illustrated by Joe Madureira.

Mark Millar returned to the Ultimates with a series of shorter miniseries, beginning in 2009 with Ultimate Comics: Avengers, which ran from August 2009 until July 2011.

The Earth-6160 version of the Ultimates began its own comic series on June 5, 2024.

General Nick Fury of S.H.I.E.L.D. establishes a strike force of government-sponsored superhumans which includes Steve Rogers (Captain America); scientist couple Henry and Janet Pym (Giant-Man and the Wasp); Bruce Banner (the Hulk) and Tony Stark (Iron Man). Together, they are based at the S.H.I.E.L.D facility the Triskelion. When Banner injects himself with the super-soldier serum and goes on a bloody rampage as the Hulk, he is eventually stopped by the other superhumans with the aid of Thor. The team then join forces with the mutants Quicksilver and Scarlet Witch and agents Hawkeye and Black Widow against the alien shape-shifters the Chitauri, who are defeated.