To prepare for the opening today of "The Avengers," you could read up on a half-century of comic books or keep your DVD player whirring with the 21st-century movies on the individual characters -- two each for Iron Man and the Hulk, one each for Thor and Captain America, a multifilm Nick Fury arc, a supporting role for Black Widow and a Hawkeye cameo, and the gang's just about all here.
Joss Whedon, co-writer, director and superhero wrangler, has added S.H.I.E.L.D. agent Maria Hill to the mix and brings the dysfunctional band together to thwart an alien invasion of Earth.
Here's a crash course in characters and one troublesome device poised to loom large in "The Avengers":
Iron Man/Tony Stark
Played by: Robert Downey Jr., left
In the comic books: Wisecracking billionaire playboy Stark suffered a chest injury, was saved by technology and then engineered an armored, armed exoskeleton that allows him to fight and fly. Corporate crimes and terrorism have kept the cocky genius busy over the years.
In the movies: "Iron Man" introduced the series of solo superhero films in 2008 with an origin story.
What's next: "Iron Man 3" is aiming for a 2013 release, with Guy Pearce rumored to join the franchise as scientist Aldrich Killian.
Played by: Samuel L. Jackson
In the comic books: Alternately a World War II hero and CIA agent, he founded S.H.I.E.L.D. (Strategic Homeland Intervention, Enforcement and Logistics Division) and acted as an intermediary for the U.S. and the United Nations with various superheroes.
In the movies: We first met Fury (and learned to wait until the very end of the credits) in "Iron Man." He brings the team together for "The Avengers" movie.
What's next: A stand-alone Nick Fury film is rumored.
Captain America/Steve Rogers
Played by: Chris Evans
In the comic books: The frail Rogers was given an experimental serum to create a super soldier fighting for the Allies in World War II.
In the movies: In the 2011 film, Rogers saved the day against the diabolical Red Skull. Cap was accidentally frozen and preserved, and eventually landed in present-day New York.
You may recall: Mr. Evans also played the Human Torch in two Fantastic Four films.
Played by: Mark Ruffalo
In the comic books: Nuclear physicist Bruce Banner was exposed to gamma rays and must wage constant battle with his emotions because, once agitated, he transforms into the rampaging green Hulk.
In the movies: Mr. Ruffalo steps in where Eric Bana and Edward Norton have tried before. Re-creating the giant green guy has been a challenge for directors Ang Lee and Louis Leterrier. Now it's Mr. Whedon's turn, with Mr. Ruffalo capturing Hulk Rage through performance capture.
Retro Hulk: Lou Ferrigno, who played TV's Incredible Hulk, voices the green guy in "The Avengers."
Played by: Chris Hemsworth
In the comic books: A Norse god among The Avengers, Thor first came to Earth in Marvel's Silver Age. He is son of Asgard ruler Odin and brother to Loki, who becomes a threat to Earth, resulting in Thor helping to form The Avengers.
In the movies: The 2011 origin story set up a collision course with Loki on Earth.
Where you are going to see him: Mr. Hemsworth is due to take on "Thor 2," but first will be seen opposite Kristen Stewart in "Snow White and the Huntsman."
Played by: Tom Hiddleston
In the comic books: Mischievous Loki was adopted by Odin and raised as Thor's brother. Jealous of Thor, Loki rebelled to become "god of evil" to the Asgardians and a threat to humans.
In the movies: Loki grew up in the shadow of Thor, then learned he was a adopted during a war with the Frost Giants. He seeks to rule Asgard and destroy his family, following Thor to Earth in the process.
Where you've seen him: Mr. Hiddleston played F. Scott Fitzgerald in "Midnight in Paris" and was an artistic soldier in "War Horse."
Played by: Jeremy Renner
In the comic books: The acrobatic master archer learned his skills growing up in a carnival and employs trick arrows and martial arts. Hawkeye started as a reluctant villain and was involved with Black Widow in an attempt to steal from Tony Stark. He soon joined the forces of good.
In the movies: Seen briefly in "Thor," helping to secure the Norse god in a S.H.I.E.L.D. operation.
Where we know him from: Mr. Renner is an Oscar nominee for "The Hurt Locker" and a member of the "Mission: Impossible -- Ghost Protocol" team.
Played by: Cobie Smulders
In the comic books: The agent has risen as high as director of S.H.I.E.L.D. and has some battles with members of The Avengers over the years. In "Civil War," Tony Stark is appointed director, with Hill as his deputy; in "Secret Invasion," she has a romance with Stark.
In the movies: Hill makes her first appearance as an assistant to Nick Fury in "The Avengers."
Where we know her from: Robin on the CBS sitcom "How I Met Your Mother."
Black Widow/Natasha Romanoff
Played by: Scarlett Johansson
In the comic books: Known as Natasha Romanova, the Black Widow was originally a Soviet spy. On missions for S.H.I.E.L.D. and The Avengers, she uses an arsenal including "widow stings," cluster bombs and martial arts. The character has been involved romantically with three Avengers: Hawkeye, Iron Man and Captain America.
In the movies: Natasha had a relatively small role in "Iron Man 2" as an assistant to Tony Stark before being revealed as a S.H.I.E.L.D. agent.
Do you recall: Ms. Johansson's character is never referred to as "Black Widow" in "Iron Man 2."
• The Tesseract, or Cosmic Cube, is an unlimited energy source that can be used as a potent weapon.
• Pepper Potts (Gwyneth Paltrow) is assistant and love interest to Tony Stark.
• Prof. Erik Selvig (Stellan Skarsgard) and S.H.I.E.L.D. Agent Phil Coulson (Clark Gregg) are characters created for the movies. Selvig is an astrophysicist and mentor to Thor's love interest, Jane Foster. Coulson is an everyman who helps Fury wrangle The Avengers.
Sharon Eberson: firstname.lastname@example.org or 412-263-1960.