Back to the Future cast: Where are they now?

THEN: Fox played the film's time-traveling protagonist Marty McFly in the Back to the Future franchise, coming in to replace Eric Stoltz after the latter had been shooting for several weeks on the film. Michael J. Fox was director Robert Zemeckis' first choice for Marty, but initially had to drop out because of other commitments.

NOW: After maintaining a busy film career throughout the 1990s, and starring in the hit sitcom Spin City from 1996 to 2001, Fox starred in the NBC sitcom The Michael J. Fox Show from 2013 to 2014. He has also appeared in a number of roles as both himself and other characters over the years, including Curb Your Enthusiasm, The Good Wife, Designated Survivor, and The Good Fight. He also lent his voice to Telltale Games' Back to the Future: The Game.

Related: Michael J. Fox says Back to the Future made him keep acting

THEN: Christopher Lloyd played the kooky Emmett "Doc" Brown, whose cry of "1.21 gigawatts" remains one of the film's most iconic lines. The impetus for Marty's adventures, it would be difficult to separate Doc Brown from the love of Back to the Future that has remained in the decades since its release.

NOW: Lloyd has continued working in film and television since Back to the Future. In 2015, he was a regular on Granite Flats and had a role on the series 12 Monkeys from 2017 to 2018. In addition, he's appeared on The Big Bang Theory, A.P. Bio, and NCIS. He has also reprised his Doc Brown role several times, including lending his voice to the video game Lego Dimensions.

Related: Great Scott! Michael J. Fox and Christopher Lloyd have a Back to the Future reunion

THEN: Lea Thompson played Marty McFly's mother, Lorraine, who unknowingly develops a crush on her own son when he travels back in time, pretending to be a man named "Calvin Klein."

NOW: After starring as the lead on the 1990s sitcom Caroline in the City, Thompson appeared on the early 2000s shows For the People and Ed. She then followed them up by playing Cathy Davis in the Jane Doe movie series for the Hallmark Channel. In recent years, she's appeared on Scorpion, Switched at Birth, Penn Zero: Part-Time Hero, and The Goldbergs.

Related: Lea Thompson reveals how she prefaces her movies to her kids

THEN: Crispin Glover played Marty's father, George, who — with Marty's help — begins a relationship with Lorraine (to ensure Marty exists in the future).

NOW: Jeffrey Weissman replaced Glover in the Future sequels. Though he's acted in mainstream films periodically since the original BTTF (notably in Charlie's Angels: Full Throttle, Alice in Wonderland, and Hot Tub Time Machine), Glover has moved into several other fields during his career. He began to release music in the late '80s and also started a company, Volcanic Eruptions, which serves as a platform for Glover to release movies he's written and produced. From 2017 to 2021, Glover had a recurring role on American Gods.

Related: Crispin Glover doesn't mind being called weird

THEN: Thomas F. Wilson played Biff Tannen, the bully who picked on George McFly and became a major obstacle as Marty attempted to unite his parents.

NOW: Wilson appeared in the sequels as Biff and other members of the Tannen family. Since then, aside from acting, he's hosted his own podcast, continued a stand-up comedy career, and done voiceover work for film, television, and video games, including a long run on SpongeBob SquarePants. He's also become known for "Biff's Question Song" and his business card, which answers all of the most frequently asked questions he's been asked over the years about Back to the Future.

THEN: Claudia Wells played Marty McFly's girlfriend, Jennifer Parker, who appears in scenes that bookend the original Back to the Future.

NOW: Parker was replaced in subsequent sequels by Elisabeth Shue, though she did reprise her role in the Back to the Future video game in 2011 and 2015. In the late-'80s, she took an extended leave from acting, but returned to it in 2008.

THEN: James Tolkan played Gerald Strickland, who worked at Hill Valley High School and, in both 1955 and 1985, was a thorn in the side of the McFlys. An authoritarian at Hill Valley, Strickland lived a life with the sole purpose of whipping as many "slackers" into shape as he could.

NOW: Tolkan has appeared on a number of television series since his time in Back to the Future. He has since been seen in HBO's Phil Spector and 2015's Bone Tomahawk.

THEN: Back to the Future may showcase Marty McFly's quest to make sure his parents meet and fall in love, but he wasn't the only McFly kid whose existence was at risk. Marc McClure played the oldest McFly child Dave. He, along with Wendie Jo Sperber (who died in 2005) as Linda, rounded out the McFly clan.

NOW: McClure has popped up in several roles throughout the years on television shows like Nash Bridges, Smallville, and The Shield. His prominent projects include 2008's Frost/Nixon and the 2017 and 2021 versions of Justice League.