The film industry is a very ruthless industry. In this, there is no scope to fail. Whatever the problem there is always a solution. Even if you have to use stand-ins and pass them as the actor. There can be many reasons that an actor is not able to continue with his character, whether it's an injury or a fight with the production or the actor died during filming.
There is an enormous amount of money involved in films and to drop them in between can cost the production. Thus, if the actor is not available then the production always find a way to replace them. Here are some of the stars replacement you might not have noticed in films and television series.
When the actor was filming "Indiana Jones and the Temple of Doom," he suffered an injury and hurt his back. But didn't stop the director as he made changes to the schedule and filmed Harrison's stunt double in his place. The stunt double and Harrison looked so similar that many times even the director got confused between them.
The movie was so low budget that the movie actors were not always available, and there were many shots when the characters were covered with gore or turned into zombies. Thus, the director decided to bring stand-ins. Until the end, total 18 stand-ins were used and were mentioned in the credit roll.
To celebrate 'Doctors Who's' 20th anniversary a special episode was released where all the doctors till then were to appear together in the episode. Since the 1st doctor had died 8 years before the episode, the role was recast. All the other doctors reprised their role except Baker, the fourth doctor. Thus, for this episode, the director used Baker's old footage from an abandoned episode. And when he refused to attend the photoshoot, producers asked Madame Tussauds for help and used baker's wax dummy in his place.
After 'Back to the Future I' the lead, George McFly, refused to return for the sequels because of some money dispute. The director, therefore, cast Jeffrey Weissman for the role. Using footage from the first film, hanging him upside down and disguising him with prosthetic makeup, Jeffery was passed on as George.
Though stand-ins are not that uncommon but they usually are not included in the final cut. In this scene, Jennifer Aniston is standing beside Joey but for few seconds, you can see her stand-in clearly.
Brandon Lee, son of Bruce Lee, died while filming because of a prop gun. Using some footages and stand-ins they finished the movie. Digital masking was also used on the stand-in.
Lena Headey plays the ultimate villain on the show. In one scene she had to walk naked in the streets of King's Landing covered in smears of filth. But how you saw is not Lena but a body double in the whole scene, merged with Headey's facial expressions.
The movie was only half filmed when star Paul Walker died. The production talked to his family and decided to continue with filming with Paul's brother, who have the same physical appearance as the actor and with the help of special effects made them look like Paul as well.