We all know the lengths that some actors go to when they are preparing for a role of making a movie.
But sometimes the make-up that they wear is so fantastic that the actor is unrecognisable when you see the film on screen.
We take a look at some of the actors who took on the extreme make-up/prosthetic challenge to make an unforgettable if somewhat unrecognisable film appearance.
- John Hurt - The Elephant Man
The Elephant Man is one of John Hurt's finest film moments as he took on the role of John Merrick in the David Lynch directed film.
The movie followed the story of Merrick, who was shunned and mistreated by the Victorian public who didn't understand or feared his disfigurement.
Hurt endured a seven or eight make-up session each day - not to mention the two hours that it took to remove.
The results were all worth it as they really captured the look of Merrick, and Hurt delivers a wonderful performance.
For his work, Hurt was nominated for a Best Actor Oscar, but missed out to Robert De Niro for Raging Bull.
- Ron Perlman - Hellboy
One of my favourite comic book adaptations comes in the form of Hellboy, which was brought to the big screen by director Guillermo del Toro.
Hellboy and Hellboy II: The Golden Army hit the big screen in 2004 and in 2008, and saw Ron Perlman take on the title role.
The movie follows a demon who is helping keep the world safe from paranormal events - oh yes, and he has to sort out his love life at the same time.
A lengthy make-up period was need for Perlman to be transformed into the loveable hero.
Without horns or with, Hellboy is one of the most striking and exciting comic book heroes to grace the big screen in many a year. Sadly, it doesn't look like a third film is going to happen.
- Doug Jones - Pan's Labyrinth
Doug Jones is also unrecognisable in Hellboy, but it is his transformations in Pan's Labyrinth that we are excited about.
Jones - whose face you rarely see on the big screen - takes on two of Pan's Labyrinth's most iconic characters... Fauno and Pale Man.
The faun guides central character Ofelia through the fantasy world, while the Pale Man is a monster who likes eating children.
Jones endured a five-hour make-up process for Fauno, which included a pair of ten-pound horns.
The Pale Man was inspired by weight that director del Toro experienced... it created one of the most terrifying film characters of all time.
- Gary Oldman - Hannibal
When you think of Hannibal you think of Anthony Hopkins as Lecter... but did you spot Gary Oldman in the 2001 movie?
Oldman played the heavily disfigured Mason Verger in the film, the only one of two of Lecter's victims to survive.
Make-up artist Greg Cannom was behind Verger's look, which involved no lips, no cheeks, or eyelids. To say that Oldman is unrecognisable is an understatement.
Oldman's name was not included in the credits when it got a theatrical release, but was added in the home-release version of the movie.
- Nick Stahl - Sin City
Sin City was one of the best movies to hit the big screen in 2005, and saw Nick Stahl take on the role of Roark Jr aka Yellow Bastard.
After an unfortunate meeting with Hartigan, Jr is left in a coma. To save his life Jr underwent a little change in appearance and becomes Yellow Bastard.
The shape of his head has significantly changed as well as his ears and teeth - you really cannot see Stahl in there are all.
Yellow Bastard is one of the movie's best characters and Stahl plays him with such menace and evil.
- Bill Nighy - Pirates of the Caribbean: Dead Man's Chest
Davy Jones was one of the new additions to the Pirates of the Caribbean cast list when Dead Man's Chest hit the big screen.
Bill Nighy took on the role of Jones, and underwent a major transformation for the part.
To create the look of Davy Jones, motion capture was used - which meant that Nighy wore a motion capture suit on set that caught all of his movements during filming.
The computer whiz kids then went to work creating the look of Jones around Nighy's performance, tentacles, and all.
- Andy Serkis - The Lord of the Rings Series
Andy Serkis is the name that you most associate with motion capture performances, as his work really has helped push this form of filmmaking forward.
Serkis shot to fame playing Gollum in the Lord of the Ring franchise, when motion capture was used to bring this complex and interesting character to the screen.
Serkis was on set in a motion capture suit where he could interact with the other actors, before repeating his performance in a studio. The computer then created the look of this popular villain.
Since then, Serkis has gone on to create more interesting characters in King Kong, The Hobbit, The Adventures of Tintin, and Rise of the Planet of the Apes.
Other actors who are unrecognisable include Tim Curry in Legend, John Leguizamo in Spawn, and Tim Roth & Helena Bonham Carter in Planet of the Apes.