- Guardians of the Galaxy (Main story and flashback)
- Star-Lord (Peter Quill) (Main story and flashback)
- Gamora (Main story and flashback)
- Drax the Destroyer (Main story and flashback)
- Rocket (89P13) (Main story and flashback)
- Groot (Main story and flashback)
- Mantis (First appearance) (Joins team)
- Yondu Udonta (Main story and flashback) (Joins team) (Death)
- Ego (Only appearance; dies) (Impersonates David Hasselhoff)
- Unnamed Abilisk (Only appearance; dies)
- Taserface's Ravagers
- Taserface (Only appearance; dies)
- Halfnut (Only appearance; dies)
- Brahl (Only appearance; dies)
- Gef (Only appearance; dies)
- Retch (Only appearance; dies)
- Narblik (Only appearance; dies)
- Scrote (Only appearance; dies)
- Vorker (Mentioned) (Full name revealed) (Death)
- Huhtar (Only appearance; dies)
- Unnamed members (Death)
- Meredith Quill (Main story and flashback) (First appearance chronologically)
- Ovette (Mentioned)
- Howard the Duck (Cameo)
- Wal Rus (Painting)
- Stakar Ogord's Ravagers (First appearance)
- Zardu Hasselfraue (Mentioned)
- Thanos (Mentioned)
- Kamaria (Mentioned)
- Stan Lee
- Officer Fitzgibbon (Only appearance; dies)
- Nova Corps
- Peter Quill's Grandfather (Cameo)
- "Adam" (Behind the scenes) (Mentioned)
- Grandmaster (Cameo)
Races and Species:
- Human-Celestial Hybrids
- Flora colossi
- Abilisks (First appearance)
- Andromeda Galaxy
- Earth (Main story and flashback)
- Sovereign (First appearance)
- Berhert (First appearance)
- Contraxia (First appearance)
- Iron Lotus (First appearance)
- Moon (Mentioned)
- Aakon (First appearance)
- Kree Homeworld (First appearance)
- Arago-7 (First appearance)
- Easik (First appearance)
- Ria (First appearance)
- Drez-Lar (Appears on a computer screen, TV, or hologram only) (First appearance)
- Terma (Appears on a computer screen, TV, or hologram only) (First appearance)
- A’askavaria (Mentioned)
- Knowhere (Only in flashback)
- Unnamed galaxy
- Ego's Planet (First appearance) (Destruction)
- Andromeda Galaxy
- Star-Lord's Helmet
- Translator Implant
- Anulax Batteries (First appearance)
- Aerorigs (First appearance) (Main story and flashback)
- Awesome Mix Vol. 2 (Destroyed)
- Quad Blaster (Main story and flashback)
- Drax's Knives
- Gamora's Sword
- Rocket's arsenal
- Universal Neural Teleportation Network (First appearance)
- Infinity Stones (Mentioned)
- Power Stone (Mentioned)
- Sony Walkman (Main story and flashback) (Destroyed)
- Space Suit (First appearance)
- Yaka Arrow Controller (Destroyed)
- Prototype Fin Yaka Arrow Controller (First appearance)
- Yaka Arrow
- Microsoft Zune (First appearance)
- '79 Ford Cobra Mustang (First appearance)
- Milano (Main story and flashback) (Destroyed)
- Sovereign Drone Ships (First appearance) (Destroyed)
- Ego's Ship (First appearance) (Destruction)
- "Talking Car" (Knight Industries Two Thousand) (Mentioned)
- Star Blasters (Cameo)
- Ravager's mining craft
- Ravager armada
The Guardians of the Galaxy work to protect the batteries of the Sovereign from invaders. Rocket steals some of the batteries and the Sovereign armada attempts to get them back. The Guardians struggle as they fly through an asteroid field, but another armada meets them on the other side. A mysterious ship appears and destroys this new armada. The mysterious ship locates the Guardians and the ship's pilot reveals himself as Ego, the father of Peter Quill. Ego invites Quill, Gamora, and Drax to his home planet. Rocket and Groot stay behind to repair their ship and guard Gamora.
Ayesha, the leader of the Sovereign, hires Yondu Udonta and his crew to recapture the Guardians. Yondu's lieutenant Taserface takes over the ship and imprisons Rocket and Yondu. Baby Groot helps them escape.
Ego explains his background as a Celestial to Quill and they start bonding as father and son. Quill starts learning how to control his powers as a half-Celestial. Meanwhile, Drax meets Ego's empath, Mantis, who eventually warns him that Ego has been killing off his other progeny. Ego explains to Quill that he, unlike his other progeny, has inherited Celestial powers. Ego tells Quill about his "purpose" in living as an immortal being, to terraform other planets into extensions of himself. Ego tries to enlist Quill to this purpose, but Quill resists when he learns that Ego killed his mother.
While Quill battles his father, the Guardians work to plant a bomb at the core of the planet Ego. The bomb kills Ego and the planet disintegrates. Yondu sacrifices himself to save Quill.
- Vin Diesel as Groot (credited as "Baby Groot")
- Director James Gunn does the motion capture for Baby Groot
Additionally, Gregg Henry and Seth Green reprise their roles from the first film as Peter Quill's grandfather and Howard the Duck, respectively. Evan Jones, Jimmy Urine, Stephen Blackehart, Steve Agee, Joe Fria, Terence Rosemore, and Mike Escamilla portray the Ravagers Retch, Halfnut, Brahl, Gef, Oblo, Narblik, and Scrote, respectively. Michael Rosenbaum, Ving Rhames, Michelle Yeoh, and Miley Cyrus portray Martinex, Charlie-27, Aleta Ogord, and Mainframe, respectively, all of whom are members of Stakar and Yondu's old Ravager team (an adaptation of the 1969 incarnation of the Guardians of the Galaxy). Frequent James Gunn collaborator Rob Zombie has another voiceover role in the film. Stan Lee makes a cameo in the film. Fred the Dog and Jeff Goldblum appear in photographs during the end credits of the film as Cosmo and the Grandmaster, respectively.
- The film was originally scheduled for release on July 28, 2017. After the commercial success of the first film, they moved this up to a May 5, 2017 release date.
- The title of the film was accidentally leaked by Kevin Feige while doing press for Ant-Man. Director James Gunn confirmed the film's title shortly afterwards on his Facebook page.
- It was earlier reported that Benicio del Toro would reprise his role as the Collector, but del Toro himself has since confirmed he was not expected to return for the sequel.
- Also, Gunn confirmed that Glenn Close would reprise her role as Nova Prime Irani Rael in the film, but she does not make an appearance, nor are the Nova Corps heavily featured.
- The film was nominated for the Academy Award for Best Visual Effects at the 90th Academy Awards.
- With a worldwide total box office gross of about $863 million, this film became the 8th-highest-grossing film of 2017.
- The film rights to Ego the Living Planet belonged to 20th Century Fox when James Gunn was writing the script. Marvel Studios struck a deal with the studio that allowed them to use Ego in the film, while 20th Century Fox was given creative freedom over the power set of Negasonic Teenage Warhead in the film Deadpool.
- The magic that Krugarr conjures up is visually similar to the magic conjurations in Doctor Strange.
- Nathan Fillion shot a cameo appearance as Simon Williams, but the footage was ultimately cut from the final film. Thus, this is the only James Gunn film that does not feature Nathan Fillion.