- Ant-Man (Scott Lang) (First appearance as Ant-Man)
- Doctor Hank Pym (Main story and flashback) (As Ant-Man in flashback only)
- Ant-Man's Crew (First appearance)
- Hope Van Dyne (First appearance)
- Cassie Lang (First appearance)
- Maggie Lang
- San Francisco Police Department (First appearance)
- Ant-Man's Ants
- Mitchell Carson (First appearance) (Main story and flashback)
- Pym Technologies/Cross Technologies (First appearance) (destruction)
- Ten Rings
- Unnamed member (Only appearance; dies)
- Unnamed separatists (Mentioned)
- S.H.I.E.L.D. (Only in flashback)
- Baskin-Robbins (First appearance)
- Dale (First appearance)
- VistaCorp (Mentioned)
- Frank (Only appearance; dies)
- Ernesto (Only in flashback)
- Emily (Only in flashback)
- Carlos (Only in flashback)
- Iron Man (Tony Stark) (Mentioned)
- Wasp (Janet van Dyne) (First appearance) (Only in flashback) (Apparent death)
- Ignacio (Only in flashback)
- Stan Lee (Only in flashback)
- Spider-Man (Peter Parker) (Mentioned)
- Bucky Barnes (Cameo)
- Leonardo DiCaprio (Mentioned)
- David Copperfield (Mentioned)
Races and Species:
- Crazy ants (Paratrechina longicornis) (First appearance)
- Fire ants (Solenopsis mandibularis) (First appearance)
- Carpenter ants (Camponotus pennsylvanicus) (First appearance)
- Bullet ants (Paraponera clavata) (First appearance)
- United States of America
- Washington, D.C. (Only in flashback)
- San Francisco
- San Quentin Prison
- Los Angeles (Cameo)
- New York
- Sokovia (Mentioned)
- Germany (Unnamed)
- Berlin (Unnamed)
- Moscow (Mentioned)
- United States of America
- Quantum Realm (First appearance)
- Yellowjacket's Suit
- Ant-Man's Suit and Helmet (Main story and flashback)
- Iron Man Armor (Mentioned)
- Wasp's Suit and Bio-Synthetic Wings (Main story and flashback)
- Pym Particles
- Exo-7 Falcon
- Pym Discs
- Pym Particle Implosion Bomb
Plot not yet listed
- Paul Rudd as Ant-Man / Scott Lang, a thief hired by Hank Pym to break into Pym Technology and stop Darren Cross.
- Evangeline Lilly as Hope Van Dyne, the daughter of Hank Pym and Janet Van Dyne. Animosity between exists between her and her father over the Ant-Man suit being passed on to Scott Lang rather than her.
- Corey Stoll as Yellowjacket / Darren Cross, the current CEO of Pym Technologies, rebranded as "Cross Technologies."
- Martin Donovan as Mitchell Carson, a figure from Hank Pym's past with connections to S.H.I.E.L.D. and Darren Cross.
- Michael Douglas as Ant-Man / Dr. Hank Pym, the founder of Pym Technology, inventor of the Ant-Man suit, discoverer of the Pym Particles, and the original Ant-Man. Dr. Pym distrusts super heroes due to something that happened to his late wife, Janet van Dyne, in the 1980s.
- Dax Griffin as young Hank Pym
Additionally, John Slattery reprises his role as Howard Stark. Gregg Turkington appears as Dale, the manager of a Baskin-Robbins. Hayley Lovitt appears as Wasp / Janet van Dyne in a non-speaking role. Stan Lee makes a cameo appearance as a bartender. Original Saturday Night Live cast member Garrett Morris makes a cameo as a cab driver. Comedian Tom Kenny provides his voice for a stuffed rabbit that Scott gives Cassie for her birthday. YouTube star Anna Akana makes a cameo as a writer who knows the Falcon. Chris Evans and Sebastian Stan reprise their roles as Steve Rogers and Bucky Barnes, respectively, in a clip from Captain America: Civil War that serves as a post-credits scene.
Jordi Mollà shot a scene as Castillo, a Panamanian general Hank steals a microfilm from in the 1980's, but the scene was ultimately cut from the movie. Patrick Wilson, Matt Gerald, and Kevin Weisman were cast in undisclosed roles before departing the project in July 2014. Wilson's role was later revealed to be that of Jim Paxton, which ultimately went to Bobby Cannavale. Jordan Peele was also cast in the film, but had to leave due to scheduling conflicts at an unknown time.
- Edgar Wright was the original director the film, but he exited the project in late May 2014 "due to differences in [Marvel Studios' and his] vision of the film." Directors Marvel considered to replace Wright included Adam McKay, Rawson Marshall Thurber, and Ruben Fleischer. Peyton Reed officially boarded the project as its new director two weeks after Wright left, while McKay joined the project as a writer.
- The film wrapped principal photography on December 6, 2014.
- The film was originally scheduled for a November 6, 2015 release, was later moved up to July 31, 2015, and then to July 17 of the same year.
- Darren Cross refers to Pym's archived adventures as Ant-Man as "tales to astonish," a reference to the comic book series that introduced Hank Pym.
- Original Saturday Night Live cast member Garrett Morris makes a cameo in the film as a cab driver. Morris portrayed Ant-Man in the classic SNL sketch "Superhero Party."
- The filmmakers originally wanted for Scott Lang to work at Chipotle, but the restaurant chain didn't particularly like the context in which their brand would've been used. Before landing on Baskin-Robbins, Jamba Juice was considered.