Of all the major Oscar categories, perhaps none are more accommodating to dark horses than the screenplay. As the category that once crowned Billy Bob Thornton a better writer than Arthur Miller, it’s hard to write anyone off.

Perhaps the most likely dark horse this year is, appropriately, “The Dark Knight,” which was not only the year’s most popular movie, but also one of its most critically successful. The Academy may previously have been loath to bestow top honors on a comic book movie, but Christopher and Jonathan Nolan’s weighty script all but reinvents the genre and has a sporting chance to be among the final five.

Despite a mixed reaction to his miserabilist “Synechdoche, New York” at Cannes, screenwriter Charlie Kaufman is an erratic Academy favorite — his last venture into metafictional trickery, “Eternal Sunshine of the Spotless Mind,” won him an original screenplay honor.

Last year’s winners for adapted screenplay, Ethan and Joel Coen, didn’t come close to replicating the critical success of “No Country for Old Men'” with this year’s darkly screwball “Burn After Reading.” Nonetheless, their track record means you can’t count them out. Likewise scribe William Monahan, who won for “The Departed” in 2006, and has received mostly good notices for the otherwise DOA “Body of Lies.”

While most of the attention to “The Wrestler” has focused on Mickey Rourke’s performance, Robert D. Siegel’s subtle, subdued script could merit mention as well. And while his backstory doesn’t quite approach Diablo Cody-levels of strangeness, Siegel’s weirdly rapid maturation (his only previous film credit is the ultra-ill-fated “The Onion Movie”) could win him support. And, while largely an improvisatory filmmaker, Mike Leigh could add to his three previous nominations with “Happy-Go-Lucky.”