Jared Leto underwent a dramatic physical transformation to portray Mark David Chapman, gaining over 50 pounds and adopting a scruffy appearance.

Christian Bale underwent an extreme weight loss of over 60 pounds to convincingly portray the emaciated and insomniac character of Trevor Reznik.

Anne Hathaway underwent a significant physical transformation for her role as Fantine, shaving her head and gaining weight to accurately portray the character's struggles and transformation.

Heath Ledger's portrayal of the Joker in 'The Dark Knight' involved extensive makeup and prosthetics to create the character's iconic look and mannerisms.

Sylvester Stallone underwent rigorous training and gained significant muscle mass to convincingly portray the boxer Rocky Balboa in the movie 'Rocky'.

Timothy Olyphant underwent a striking physical transformation for his role as Agent 47, shaving his head and eyebrows to embody the character's distinct appearance.

Meryl Streep underwent extensive makeup and prosthetics to accurately portray the physical characteristics and mannerisms of Margaret Thatcher in the movie 'The Iron Lady'.

Joaquin Phoenix underwent a significant physical transformation for his role as Arthur Fleck in 'Joker', gaining weight and adopting a distinctive accent to embody the character's descent into madness.

Christian Bale underwent an intense training regimen and adopted a specific diet to convincingly portray the physicality and strength of Batman in the 'Dark Knight' trilogy.

Ralph Fiennes underwent extensive makeup and prosthetics to create the iconic and menacing appearance of Voldemort in the 'Harry Potter' film series.

Charlize Theron underwent a striking physical transformation for her role as Imperator Furiosa, shaving her head and gaining weight to embody the character's strength and resilience.

Tilda Swinton underwent extensive makeup and prosthetics to create the ethereal and otherworldly appearance of the White Witch in the movie 'The Chronicles of Narnia: The Lion, the Witch and the Wardrobe'.

Christian Bale underwent a significant weight loss and adopted a specific diet to convincingly portray the lean and muscular physique of Patrick Bateman in the movie 'American Psycho'.

Josh Brolin underwent extensive makeup and prosthetics, including shaving his head, to create the imposing and powerful appearance of Thanos in the 'Avengers' film series.