The 20th Century Fox film is a follow-up to the 2011 reboot "Rise of the Planet of the Apes," which starred James Franco. For now, the sequel's plot is being kept under wraps, but "Dawn" apparently takes place 15 years after "Rise," with Andy Serkis reprising his motion capture role as the hyper-intelligent ape Caesar.
Clarke's role has yet to be revealed, according to The Hollywood Reporter. Matt Reeves ("Cloverfield") is directing.
"Dawn" is tentatively scheduled to begin production this spring.
The original "Planet of the Apes," which starred Charlton Heston, was released in 1968, and spanned a number of sequels, a TV spin-off, an animated series, and more. It was remade by Tim Burton in 2001.
In addition to the best picture nominee "Zero Dark Thirty," Clarke was recently seen in John Hillcoat's "Lawless," and will soon appear alongside Leonardo DiCaprio, Tobey Maguire and Carey Mulligan in Baz Lurhmann's "The Great Gatsby."