LOS ANGELES (AP) — Heath Ledger is getting a fond tribute from his collaborators on "The Dark Knight."

The end credits of the "Batman Begins" sequel include a farewell note to Ledger, who died in January from an accidental overdose of prescription drugs; and to special-effects technician Conway Wickliffe, who was killed last September in a stunt-car accident.

"In memory of our friends Heath Ledger & Conway Wickliffe," reads the tribute included in the credits, which went up Thursday on the Warner Bros. publicity Web site.

Ledger plays the villainous Joker in "The Dark Knight," who begins a reign of terror on Gotham City that pits him against conflicted hero Batman (Christian Bale).

Arriving in theaters July 18, the movie reteams Bale with director Christopher Nolan and returning co-stars Michael Caine, Morgan Freeman and Gary Oldman. Joining the cast are Aaron Eckhart and Maggie Gyllenhaal.

Beginning months before Ledger's death, his frenetic performance and demented-clown makeup have been a cornerstone of the marketing campaign for the film.

"I needed a phenomenal actor, but he also had to be someone unafraid of taking on such an iconic role," Nolan says in the production notes for "The Dark Knight." ''Heath created something entirely original. It's stunning, it's captivating. ... It's going to blow people away."