Josh Brolin plays a young Tommy Lee Jones in Men in Black 3. From Ewan McGregor to Rob Lowe, see other actors who stepped in to established parts—and what their forebears thought of it. In the third installment of the Men in Black series, Will Smith’s Agent J travels back to 1969 to prevent the assassination of his partner, Agent K (Tommy Lee Jones). But when Smith gets there, he encounters a much-younger K—played by Josh Brolin. Forgetting for a moment that Brolin is 44 and in 1969, Tommy Lee Jones was just 23 (a year away from making his movie debut in Love Story), Brolin’s impersonation in MIB3 is eerie. "I think the tough thing about Tommy's voice is he's all over the place,” Brolin told WENN recently. “It's like he's improvising his voice and it's still cultivating into something. It's like an instrument that's been played by nobody, where somebody asks you to not only learn how to play it but make an album in two months that everybody will hear." As for Jones’s review of the performance, Brolin’s nervous: “I still don't know if Tommy liked it or not." Sony Pictures To play young Magneto in the 2011 prequel X-Men: First Class, Michael Fassbender had a big helmet to fill: Sir Ian McKellen’s. But rather than base his performance on what McKellen had done in the previous X-Men movies, Fassbender returned to the original source material—the Marvel comics. "Initially, I thought to myself, ‘Should I study a young Ian McKellen, study his voice and his physicality?'” Fassbender said in an interview last year. “So I spoke to [director] Matthew [Vaughn] about it, I think it was in our first or second meeting, and he wasn't so keen on the idea. He wanted me to use my own voice and take it from there, so we just wiped the slate clean.” It also helped that Fassbender was cast opposite James McAvoy, who portrayed a younger (and hairier) version of Patrick Stewart’s Dr. Charles Xavier. 20th Century Fox / Everett Collection It’s a very brave (or very foolish) actor who is willing to take on a character that won someone else an Academy Award—especially when that that character is one of the great screen villains of all time. But Gaspard Ulliel understood the pitfalls of portraying young Hannibal Lecter in Hannibal Rising. “Obviously I knew that the audience would look for some similarities with Anthony Hopkins, so one part of the preparation was to observe Anthony Hopkins,” the French actor admitted. “But the idea was more to just pick a few details in his performance and then add it to my own character…..There are a few things that you can clearly see in Silence of the Lambs, for example, all the eye movement and the blinking and also his stillness can be very scary sometimes.” Alas, the performance wasn’t that convincing or terrifying. As The New York Times said in its savage review: “He’s like Anthony Hopkins’s brain-damaged sibling.” Orion Pictures / Everett; MGM / Everett Ewan McGregor’s performance as the young Obi Wan Kenobi was one of the few elements of the three Star Wars prequels that critics and fans didn’t despise. Though the two actors neither look nor sound alike, McGregor projected Guinness’s same cool Jedi demeanor. (Also, he worked the beard.) And both men hated the franchise. Guinness famously resented that Obi Wan became the defining role of his career and McGregor had similar reservations about appearing in a blockbuster. “The Jedi Knights have got a sense of what's going to happen, so they don't freak out or panic or anything. But after a while I noticed the only thing I was doing was frowning a lot,” he told Interview. “That's a worry when you shoot for three-and-a-half months.” And just in case his Dark Side feelings weren’t clear, McGregor added, “It was also a tedious film to make.” Lucasfilm Ltd. / Everett; 20th Century Fox / Everett How did Rob Lowe prepare to play the younger version of Robert Wagner’s No. 2 in The Spy Who Shagged Me? “I just watched a lot of Heart to Heart reruns,” the actor admitted. “I grew up with him on TV.” And while Wagner was flattered by the astonishing impersonation—“That’s my boy, Rob Lowe,” he told Larry King in 2002—he may not be Lowe’s No. 1 fan. As Lowe recounted in his memoir, Stories I Only Tell My Friends, while saying good night to Wagner, Cary Grant, and Prince Rainier of Monaco at a charity dinner one night, he claimed to have overheard Wagner tell the others, "Ya know, guys, I think that kid's banged every one of our daughters." New Line Cinema / Everett Collection Three years after River Phoenix played Harrison Ford’s son in The Mosquito Coast, he took on one of Ford’s most iconic roles, playing a teenage Indiana Jones in Indiana Jones and the Last Crusade. As for how he found his inner Indiana, Phoenix told an interviewer: “I would just look at Harrison. He would do stuff and I would not mimic it but interpret it younger. Mimicking is a terrible mistake that many people do when they play someone younger, or with an age difference. Mimicking doesn't interpret true, because you can't just edit it around.” But Phoenix (who died four years later, at 23) never thought he might inherit the role someday: “I don't think that anyone [but him] could ever do justice to the character of Indiana Jones. A production without Harrison would never be that good. I think it should remain the way he does it.” Paramount / Everett Collection The first time Leonard Nimoy met Zachary Quinto, who was up to play young Mr. Spock in the 2009 Star Trek reboot, it was in an elevator. “I said to him, 'Do you have any idea what you're getting into?'” Nimoy told People. After sharing some funny stories about rabid Trekkies, Nimoy called director J.J. Abrams and gave his blessing. “I think he's terrific. I think the resemblance works. Most importantly, he has an interior life,” Nimoy told Abrams about his successor. “I like smart people.” As for Quinto’s fears about taking on the role, it came down to one thing: “The eyebrows for me were probably the biggest challenge,” he admitted, “just because my eyebrows are such a big part of my face. There's really no way around it and to lose three quarters of them for six months...!” Paramount / Everett Collection Thirty years and three sequels after Anthony Perkins played the title role in Alfred Hitchcock’s Psycho, we finally learned the origin of Norman Bates’s incredible Oedipal complex in Psycho IV: The Beginning. Though Perkins appeared in the made-for-TV movie, the role of young Norman was portrayed by Henry Thomas, who famously played Elliott in E.T. And while Perkins gave Thomas a few pointers about the character, he was not possessive of the role. “He just gave me a few broad strokes and told me to play the character real,” Thomas said, “that was it." Universal Pictures / Everett; MCA Television Entertainment / Everett While Marlon Brando won a Best Actor Oscar for playing Don Corleone in The Godfather, Robert De Niro had to settle for a Best Supporting Actor nomination when he portrayed the younger Vito in The Godfather Part II. In an interview with Esquire last year, De Niro paid tribute to Brando’s work, saying, “No matter what Marlon did, he was always interesting.” But the two men didn’t ever compare notes on the role. “Marlon and I never talked about our performances in The Godfather. What was he going to say? We knew each other. I spent time on his island with him. But you don't talk about acting. You talk about anything but acting. I guess the admiration is unspoken.” Considering how Butch Cassidy and the Sundance Kid ended (SPOILER ALERT: they didn’t escape that hail of bullets) there was no chance of having Paul Newman and Robert Redford to star in a sequel. But 10 years after the film’s release, Hollywood produced one of the first prequels—Butch and Sundance: The Early Years starring Tom Berenger in the Newman role and William Katt taking on Redford. (SPOILER ALERT: Don’t bother renting it.) In between, Newman and Redford did reunite onscreen, in The Sting. And the pairing was so successful once again that the studio waited a full decade before making a sequel—with Jackie Gleason and Mac Davis.