I always forget that Inigo Montoya starred inCriminal Minds.

One of the wildest things about movies is watching actors absolutely lose themselves in their roles.

Austin Butler and Bill Skarsgård, side by side, with Austin Butler in a vintage-style outfit and Bill Skarsgård in futuristic armor

Left: Julie Walters as Molly Weasley in "Harry Potter." Right: Julie Walters as Rosie in "Mamma Mia!"

Donald Glover in casual clothing and Harry Styles as a period character in a costume with an ascot and jacket

John Travolta on the left as Danny Zuko from "Grease" in a leather jacket; on the right, as Edna Turnblad from "Hairspray" in a housecoat

Side-by-side images showing Mandy Patinkin as Inigo Montoya in "The Princess Bride" (left) and a modern photo of Mandy Patinkin (right) in a casual shirt

Joaquin Phoenix, left, in a retro setting with a cigarette and a microphone, and Joaquin Phoenix, right, dressed as the Joker with clown makeup in a bathroom

Stanley Tucci as Caesar Flickerman, looking serious in a suit and tie, and Stanley Tucci as George Harvey, wearing glasses and a sweater with a plaid scarf

Tilda Swinton shown in two images: on the left in modern attire with loose blonde hair, on the right portraying Jadis the White Witch with a crown and frizzy hair

Catherine O'Hara in a split image. Left: as Kate in "Home Alone," surprised expression. Right: wearing a white outfit with a statement necklace, red lipstick, and wavy hair

Two images of Bryan Cranston: Left, serious in a striped shirt as Walter White from "Breaking Bad." Right, surprised in a plaid shirt holding lottery cards from "Malcolm in the Middle."

Colin Farrell in split-screen: on the left, transformed as the Penguin in "The Batman" with makeup and prosthetics, and on the right, in a red shirt from "Horrible Bosses."

Lily James in a medieval-style gown with flowers in her hair and also in a modern setting, with a blonde wig, wearing a sleeveless top as Pamela Anderson

Close-up of Jared Leto as the Joker in makeup and costume, next to Jared Leto in prosthetics as Paolo Gucci wearing a blue checkered suit and pink shirt

Split image of Christian Bale in "The Machinist" on the left and in "Vice" on the right

Margot Robbie pictured in two different roles: one smiling in beachy attire with a large hat and jewelry, the other as a historical figure with elaborate costume and ruff collar

Idris Elba in a suit and tie on the left, and as the character Macavity in "Cats" wearing a hat and fur coat on the right

Images show an actor in two roles: as a heavily made-up character, topless with prosthetics, and in a separate image, casually dressed in a patterned shirt