Spoiler warning: Please don't read this if you don't want to know details about "Avengers: Endgame" and the film's many cameos and callbacks.
The cast of "Avengers: Endgame" is so massive and features so many characters that have been spread out across 22 films for more than 10 years, even the most diehard fans can be forgiven for forgetting who some of these people are. Rene Russo was in these movies? Who's that spiky-haired kid at the end? They even got Robert Redford! These callbacks, as presented in chronological order of the film, include any recurring or one-off character who hasn't been around since "Infinity War."
Laura Barton - Linda Cardellini
Who is she? - Hawkeye's wife
What is she doing? - She appears during the film's sobering opening sequence, in which Hawkeye's entire family is dusted by Thanos's snap.
When did we last see her? Laura was only ever seen in "Avengers: Age of Ultron" during a rare peek inside Hawkeye's private, personal life.
Who is he? The co-director of the movie making his cameo
What is he doing? He's one of the poor souls sharing his story in Captain America's support group five years removed from Thanos's snap. Maybe we can assume his brother got dusted.
Who is he? The creator of the character Thanos in the original comic books
What is he doing? He sits beside Joe Russo during the support group scene.
When did we last see him? Starlin has been a polarizing figure in the history of Marvel Comics fandom, so it's nice to see him make this cameo.
Storage Facility Guard - Ken Jeong
Who is he? The guard who spots Ant-Man after he manages to come back from the Quantum Realm
What is he doing? He has to do a quick double- take after looking at his security monitor.
When did we last see him? Jeong's appearance keeps with the tradition of "Community" actors making cameos in Russo Brothers films.
Valkyrie - Tessa Thompson
Who is she? Real name Brunnhilde, an Asgardian warrior who is part of an elite, ancient group of warriors called the Valkyrie.
What is she doing? Valkyrie managed to survive Thanos's snap, and she's spent the last five years on Earth in New Asgard as a dock worker, soon to be queen.
When did we last see her? Though she wasn't seen in "Infinity War," Valkyrie managed to lead the remaining, surviving Asgardians to safety in escape pods prior to Thanos decimating the Statesman.
Korg and Miek - Taika Waititi
Who are they? One is a pile of rocks, the other is an insect with knives for hands. They’re also very good friends.
What are they doing? They and Thor together throw back some beers at New Asgard and taunt kids playing "Fortnite."
When did we see them last? They were some of the standouts of “Thor: Ragnarok” when Thor becomes a gladiator for the Grandmaster.
The Ancient One - Tilda Swinton
Who is she? Doctor Strange’s mentor and leader of the Master of the Mystic Arts
What is she doing? She’s found in 2012 during the Battle of New York and offers up the Time Stone to Bruce Banner when she realizes Strange willingly gave Thanos the Time Stone for a good reason.
When Did We Last See Her? Her former student Kaecilius defeated her during the events of “Doctor Strange.”
Alexander Pierce - Robert Redford
Who is he? A HYDRA secret agent who had infiltrated the top ranks of S.H.I.E.L.D. and the U.S. Government
What is he doing? After the Battle of New York when the characters travel back in time to 2012, we get a moment not seen during "The Avengers" in which Pierce tries to commandeer the Tesseract from the Avengers after capturing Loki.
When did we last see him? He was killed by Nick Fury during "Captain America: The Winter Soldier."
Jasper Sitwell, Brock Rumlow, Jack Rollins – Maximiliano Hernandez, Frank Grillo, Callan Mulvey
Who are they? HYDRA double agents. Rumlow is also known as Crossbones.
What are they doing? In a great nod to a brilliant, elevator fight scene during “Captain America: The Winter Soldier,” they’ve swept in and taken Loki’s scepter, leading Cap to try and steal it back. The scene even makes a nod to a controversial arc in the comics, in which Captain America becomes a HYDRA agent as well.
When did we last see them? All three were seen in “Captain America: The Winter Soldier," but only Rollins made it out alive, though he was incapacitated by Black Widow.
Frigga - Rene Russo
Who is she? Thor’s mom
What is she doing? She gives the fat, Lebowski Thor a pep talk when he goes back in time to Asgard to find the Reality Stone.
When did we last see her? In “Thor: The Dark World,” she’s killed in a fight with Malekith. Thor happens to run into her on the day she dies and is tempted to change the past and warn her.
Jane Foster - Natalie Portman
Who is she? Thor's ex-girlfriend
What is she doing? Portman gets billing during the end credits, but her brief appearance is actually a scene from "Thor: The Dark World" when her body still held the Reality Stone, or Aether.
When did we last see her? Portman left the franchise after "The Dark World," but she's been mentioned in passing in "Avengers: Age of Ultron" and "Thor: Ragnarok."
'70s Car Man - Stan Lee
Who is he? 'Nuff said
What is he doing? Lee dons some period appropriate facial hair and roars onto the screen in a muscle car shouting, "Make love, not war" ahead of the film's 1970 time travel sequence.
When did we last see him? Lee also managed to make a "Captain Marvel" cameo before his death in November 2018.
Woman in Elevator - Yvette Nicole Brown
Who is she? An employee at the S.H.I.E.L.D. facility in 1970
What is she doing? She gets a good look at the future Steve Rogers and Tony's unruly facial hair and gets suspicious.
When did we last see her? She's yet another "Community" star making a Russo brother cameo.
Howard Stark - John Slattery
Who is he? Tony Stark’s dad
What is he doing? When Tony and Cap go back in time to 1970, shortly before Tony was meant to be born, father and son have a heart to heart about kids and the future. Howard Stark also asks Tony if he’s a “beatnik.”
When did we last see him? John Slattery’s Howard Stark has appeared at various ages with different shades of hair, but he was last seen in “Captain America: Civil War” in flashback footage.
Peggy Carter - Hayley Atwell
Who is she? – One of the founders of S.H.I.E.L.D. and the love of Steve Rogers’ life
What is she doing? Captain America finds her office when he travels back in time to 1970 and spies her from the other room, and the two lovebirds find their way back to each other in the end.
When did we last see her? Though she’s been mentioned and even seen in a photograph in “Captain America: Civil War,” her last appearance was in “Ant-Man.” She was present in 1989 when Hank Pym confronts Howard Stark for using his research and resigns his post.
Edwin Jarvis - James D'Arcy
Who is he? The household butler of the Stark family
What is he doing? He briefly appears alongside Howard Stark during the 1970 time travel scene.
When did we last see him? Edwin Jarvis has actually never appeared in the Marvel Cinematic Universe but he has appeared in the "Agent Carter" TV show. This is actually the first time the MCU has ever acknowledged a character in one of the many Marvel TV shows.
Happy Hogan - Jon Favreau
Who is he? Tony Stark's personal chauffeur and closest friend, not to mention a fan favorite since the very beginning
What is he doing? He has a touching scene with Tony's daughter after Iron Man's death.
When did we last see him? Unless you count an "Infinity War" deleted scene, Happy was last seen in "Spider-Man: Homecoming" as a go-between for Peter Parker and Tony.
Maria Hill - Cobie Smulders
Who is she? – The former Deputy Director of S.H.I.E.L.D.
What is she doing? Not much, but we briefly see her at Tony’s funeral.
When did we last see her? Technically, she was dusted in the post-credits scene of “Infinity War,” but she last appeared in earnest in “Avengers: Age of Ultron” and will be seen in “Spider-Man: Far From Home.”
Aunt May - Marisa Tomei
Who is she? Peter Parker's aunt
What is she doing? She's seen paying her respects at Tony's funeral.
When did we last see her? In "Spider-Man: Homecoming," she was getting awfully cozy with Happy Hogan.
Ramonda - Angela Bassett
Who is she? The Queen Mother of Wakanda and T'Challa's mother
What is she doing? She can be seen reunited with T'Challa overlooking Wakanda at the end of the film.
When did we last see her? Though we visited Wakanda in "Infinity War," she's stayed on the sidelines since "Black Panther."
Harley Keener - Ty Simpkins
Who is he? An ordinary kid, Harley met Tony when he was just a boy as Tony tried to repair his suit during "Iron Man 3."
What is he doing? He's seen standing quietly alone at Tony Stark's funeral.
When did we last see him? Actor Ty Simpkins was no more than 11 years old when we saw him in "Iron Man 3," so to see a teenage boy at Tony's funeral was a callback that surely caught many by surprise.