Michael Caine recalled his time filming The Dark Knight with late actor Heath Ledger, in his memoir, Don’t Look Back, You’ll Trip Over: My Guide to Life.

“He was a lovely guy, very gentle and unassuming,” wrote the Interstellar star in his book.

The Batman Begins actor went on to explain that once Ledger’s hair and makeup for psychopath villain was completed, his portrayal of the Joker was “chilling” to see.

“The smeared makeup, the weird hair, the strange voice. It was chilling. Absolutely floored me the first time I saw him in action I was terrified,” Caine recalled.

Previously in an interview with The New York Times, the deceased Australian actor, described Joker as a, “psychopathic, mass-murdering, schizophrenic clown with zero empathy” noting that the demanding role also affected his sleep.

The Oscar-winning actor also noted that Ledger’s impressive performance inspired others on set to “raise our game.”

Caine in his memoir also looked back on time when he received the news of Ledger’s passing saying that it was “absolutely awful” and “it still makes me sad to think of it.”

Ledger received a posthumous Best Supporting Actor Oscar at the 2009 Academy Awards, for his role in Christopher Nolan’s film starring Christian Bale as Batman.

Ledger, was found dead January 22, 2008 at the age of 28 in his apartment. A toxicology report revealed a fatal mix of prescription drugs in his system.

“Even though his career was cut short so soon, he’ll be remembered as a great actor, I believe,” Caine said.