Sci-Fi Actor Replacements That Were Actually For The Best

It's all too easy to miss your big chance in Hollywood, whether it's by ending up in a flop through no fault of your own or missing the wrong phone call. It's a career tragedy that can happen to anyone, and it creates agonizing memories for stars still at the top of their careers. Just ask Bill Murray about the time he did pick up his phone and wound up with a gig in "Garfield." That involved a mix-up over last names, but it goes to show that anything can happen to anyone.

The good news? Not every movie madness mixup ends in disaster. One star's missed call might be another's golden hour. A tragedy behind the scenes can create an opportunity for a fresh and far better take on a character. Science fiction definitely isn't exempt from Hollywood chaos, and in the case of some of our favorite movies, these butterfly effects give us a chance at a whole new world of wonder we could never have expected. These are the last minute screw-ups and panic decisions that made some movies immortal.

Trivia fans know that the actors playing the Marines in James Cameron's "Aliens" spent several weeks together in rehearsal, customizing their character's armor and building the natural camaraderie that comes through on screen. That same trivia often notes that Michael Biehn came in late, and he even inherited some other guy's armor instead of putting together his own.

That "other guy" was "The Warriors" star James Remar, who needed to be replaced several weeks into filming. Facing a drug charge, he was removed from the production and Biehn spent a fast weekend flying to England to pick up the slack after producer Gale Anne Hurd personally called him. A Cameron veteran, Biehn's sturdy, unflappable Corporal Hicks becomes Ripley's bedrock for the movie's back half. He matches up to Sigourney Weaver's charisma so well that we never notice he feels a little more quiet with his fellow Marines. And, yes, we're still mad that he's not getting the redemption he deserves in the still-canceled Neill Blomkamp "Alien" film.

Martial arts star Jean-Claude Van Damme was still building his film career when the classic action movie "Predator" started filming and director John McTiernan recruited Van Damme to add his lithe athletics to the alien sportsman. That's when the trouble started. Stacked up next to the beef supreme cast, which included Arnold Schwarzenegger and Jesse Ventura at their apex, a quick little guy — Van Damme stands a normal 5 feet, 10 inches but his opponents were all 6-foot-plus and built like Soviet Brutalist architecture — loses a lot of menace. Reportedly, his version of the Yautja suit wasn't much fun, either.

Enter Kevin Peter Hall, who previously filled a Bigfoot suit for the far lighter "Harry and the Hendersons." At 7-foot-plus, the new hunter towered over these Earthling meat puppets. Though rarely in the same shot with anyone long enough to pull out a ruler, it wasn't hard to tell that this Yautja provided the apex predator the film needed to be awesome. Not only does Hall get to cameo with his own face during the helicopter rescue at the end, but he returned as another Yautja, and their elder, for "Predator 2." Hall died in 1991, but what he did for this sci-fi icon will remain immortal.

The giant, all too lifelike Tyrannosaur Rex that stands triumphant at the end of "Jurassic Park" serves as the real icon of the entire franchise. No offense, or maybe full offense, Chris Pratt. You decide. But she — remember, all the dinos at least start out female — almost didn't get her big moment, and if she hadn't, "Jurassic Park" possibly wouldn't have evolved into such a dino-sized juggernaut.

The original finale was a passive kind of Chekhov's gun. Alan Grant (Sam Neill) and the kids needed to navigate that glorious lobby — with all its dino skeletons on display — to get away from the cleverest girls on the island, the velociraptors. Destabilized by all the goings on, a T. rex skull was going to fall on the last hungry raptor, letting the humans survive. A nice visual joke about the circle of life, sure, but not exactly gripping stuff. A quick rewrite, bearing in mind just how well the new CGI and practical creature effects were working out, and Rexy — also known as Roberta by visual effects wizard Phil Tippett's crew — got her own Sigourney Weaver-style heroine moment for the ages. That's our girl.

Terrence Howard gave us a pretty good James 'Rhodey' Rhodes in "Iron Man." He's a stoic foil to Tony Stark's (Robert Downey Jr.) antics and the only sane man in town. Until Agent Coulson (Clark Gregg) shows his stripes, anyway. Howard didn't return for "Iron Man 2," with the stated real reason being a dispute over his paycheck. Considering Hollywood's detestable tendency to pay people of color and women far less than they deserve, it's an honest possibility. His departure came late in pre-production, however, and Don Cheadle had to sign on fast, with little idea of what would come next.

The results are, no disrespect to Terrence Howard's solid film chops, a glam-up. Cheadle takes Howard's stoic nature towards Stark and turns it into a lively unflappability that is, sometimes, the only thing on Earth that can deflate the infamous billionaire playboy genius when he's running full steam. Colonel Rhodes is now Cheadle's signature role — not to overshadow his Academy Award-nominated work in "Hotel Rwanda" — so keyed to him that we're both annoyed by and impressed by the revelations of "Secret Invasion."

If "Star Wars" taught us anything, besides that you can craft a compelling story about any background character, it's that taking a percentage of a guaranteed moneymaker will feed your grandkids' great-grandkids for decades to come. Matt Damon knew that when James Cameron talked to him about his "Avatar" project, offering a 10% cut of the box office profits. But Damon, an all-around decent guy, was in the middle of a "Bourne" film, with more on the way. He declined, eyes open, regretful about missing a chance to work with Cameron.

Sam Worthington, meanwhile, was a fresher Aussie face with nowhere to go but up. A mean-spirited attitude out there that suggests all he's been good for is Cameron's franchise, an assertion belied by a trail of fantastic work on acclaimed miniseries like "Manhunt: Unabomber" and "Under the Banner of Heaven" in between his CGI-heavy shoots for the sprawling franchise. It's also true that he lends "Avatar" a steady, new-guy humility that helps undercut the White Savior themes in a way Kevin Costner's ego could never handle. He was the right choice for "Avatar," and it still shines blue — we mean through.

Spike Jonze's "Her" blends the myth of Pygmalion with Greg Bear's "Blood Music." As the reclusive Theodore (Joaquin Phoenix) helps his voice-only AI assistant become her own person, she, too, melds with others of her kind to achieve a technological singularity. It's heady stuff about the way our relationships enable us to grow as people, but post-ChatGPT, it hits a little differently. In any case, "Her" rides or dies on your feelings about Samantha's voice, no multi-fingered visual glitches necessary. She's Scarlett Johansson, in full gentle purr mode, and that's pretty hard to resist.

But Samantha was originally voiced by, well, Samantha. Samantha Morton, that is, an English actor with a sweet, earthy voice that comes through the best in her role as a troubled precog in "Minority Report." It created a dynamic with Phoenix that didn't work for Jonze, and Johansson redubbed the role in post-production. It's an upgrade that suits the intimate tone Ted is emboldened by to become a little more extroverted. Some of us wonder if Morton could've landed the intimacy of intellectual evolution more strongly. Either way, the film rates as fascinating stuff that digs into the best of science fiction's potential.