THEN AND NOW: The cast of 'Back to the Future' 35 years later

Fox played protagonist Marty McFly in the "Back to the Future" franchise, replacing Eric Stoltz when producers fired the actor after several weeks of filming.

Marty helps his eccentric older friend, Dr. Emmett "Doc" Brown, test out his new time machine, but is accidentally transported back in time 30 years (to the year 1955). When he interferes with his parents' first meeting, Marty must race against the clock to set them up together (before his existence is erased).

Fox was already well-known for his role on the sitcom "Family Ties" when "Back to the Future" came out, but he became a megastar thanks to the sci-fi franchise's success. Apart from reprising his role as Marty in the film's two sequels, he appeared in mainstream '80s movies like "Teen Wolf" and "The Secret of My Success."

The actor then scored another popular sitcom role on the show "Spin City," but began to slow down his career after revealing that he had been diagnosed with Parkinson's disease in 1998. In 2000, Fox announced his retirement from acting and founded the Michael J. Fox Foundation for Parkinson's Research.

However, he eventually returned to entertainment with his NBC sitcom, "The Michael Fox Show," and has since guest-starred on series like "Curb Your Enthusiasm," "Designated Survivor," and "The Good Wife."

Emmett "Doc" Brown was the driving force behind Marty's adventure and invented the first time machine by renovating a DeLorean sports car.

Marty later finds the quirky inventor in 1955 and seeks his help returning to the present.

Lloyd has played Doc several more times outside of the "Back to the Future" movies, appearing as the character on the short-lived TV series of the same name and voicing him in multiple video games. He has also continued to pop up in major films like "The Addams Family," "Clue," and "Who Framed Roger Rabbit."

The actor's most recent leading role came as The Missionary on Syfy's series "12 Monkeys," but he's also appeared on "A.P. Bio," "The Big Bang Theory," and "NCIS."

Lea Thompson played Marty McFly's mother, Lorraine, who unknowingly develops a crush on her own son when he travels back in time and poses as a boy named Calvin Klein.

Thompson starred on the '90s sitcom "Caroline in the City," and went on to lead the "Jane Doe" film series on the Hallmark Channel. From 2011 to 2017, she played Kathryn on the Freeform series "Switched at Birth." Thompson also made an appearance in the 2018 Netflix movie "Sierra Burgess Is a Loser."

The actress has made time to forge a career behind the camera, making her directorial debut with the 2006 TV movie "Jane Doe: The Harder They Fall." She has been a TV and film director ever since, notably directing her daughters Madelyn and Zoey Deutch in the 2017 film "The Year of Spectacular Men."

Crispin Glover played Marty's nerdy father George, who eventually begins dating Lorraine with Marty's help (and ensures that his three children continue to exist in the future).

Like Wells, Glover played both the teenage and adult versions of George in "Back to the Future."

Unlike many of his costars, Glover did not return for the "Back to the Future" sequels (instead, he was replaced by actor Jeffrey Weissman).

However, he's still appeared in many notable films since, like David Lynch's "Wild at Heart," the 2000 film version of "Charlie's Angels," and Tim Burton's "Alice in Wonderland." Most recently, he's had a recurring role as Mr. World on the Starz show "American Gods."

Wilson played Biff Tannen, the bully who picked on both generations of McFlys and often got in the way of Marty helping his parents fall in love.

Wilson starred as Biff and several of his relatives in the "Back to the Future" sequels. Since then, the actor has continued to make a name for himself in the entertainment industry through acting in "Ed," "Freaks and Geeks," and "Help Me Help You." Wilson has also done a significant amount of voice work, from "The New Batman Adventures" to a long run on "SpongeBob SquarePants."

From 2018 to 2019, the actor portrayed Hank Heywood on the CW DC Comics show "Legends of Tomorrow."

Jennifer is Marty's girlfriend in the present-day timeline. Although Jennifer doesn't appear in much of the movie (since Marty spends most of it in 1955), she reappears in the last scene — just as Doc arrives to tell her and Marty that they need to go "back to the future."

Because her mother was fighting stage-four cancer when "Back to the Future Part II" came around, Wells took a hiatus from acting and told Universal that she would not be able to play Jennifer in the franchise's sequels. Although she was replaced by actress Elisabeth Shue in subsequent films, Wells later reprised the role in the 2011 and 2015 "Back to the Future" video games.

In the early 1990s, she also started Armani Wells, a clothing store that (as of 2018) she still manages. Although Wells has mostly taken a longterm leave from acting, she recently had a role in the 2019 thriller "Vitals," and is set to appear in multiple upcoming projects — including the horror film "Room and Board" and the action movie "Quinn."

Strickland was an uncompromising educator, and often referred to Marty and his father as "slackers."

After playing a domineering principal in "Back to the Future," he portrayed another no-nonsense character (Stinger) in the 1986 hit action film "Top Gun." The actor signed on for both "Back to the Future" sequels, and has since taken on film roles in HBO's "Phil Spector" and the 2015 western "Bone Tomahawk."

After interacting with his parents in the past, Marty's '80s family life changes. His older brother, Dave, half-heartedly works at Burger King at the beginning of the movie. However, after Marty's time-travel adventures, Dave now appears more confident and works a white-collar job.

McClure has guest-starred on a number of TV series over the years, appearing on shows like "ER," "Smallville," and "The Shield."

The actor's other notable film roles include playing Boris in the 2003 remake of "Freaky Friday," and portraying Officer Ben Sadowsky in the 2017 DC movie "Justice League."

Marty's older sister Linda also changed by the end of the movie, becoming more confident, getting a job at a boutique, and attracting multiple love interests.

The 46-year-old actress had been an advocate for cancer care since learning that she had breast cancer in 1997. In 2001, she opened weSPARK, a California-based cancer center devoted to "enhancing the quality of life for cancer patients, their families, and friends."

In terms of acting, Spoker returned for "Back to the Future Part III," and had notable roles on the TV series "Babes," "Hearts Afire," and "Women in Prison."