If 2007 came to a close at the movie theater with a marathon of dark titles — documentaries about the war on terror and narratives focused on vengeful monsters — then 2008 is beginning with an assortment of jaunty stories that let in the light and bring back the fun. Big stars are going silly, superheroes are once again innocent, and even Guantanamo Bay is the setting for a fictional comedy.

It all begins on March 28, with “Run Fatboy Run.” The directorial debut of David Schwimmer (yes, that’s Ross from “Friends”) is a whimsical fairy tale about an out-of-shape, middle-age chap (Simon Pegg) trying to win back his ex-fiancée by beating her new love interest in a London marathon. It’s just the kind of good-natured comedy one sees far too rarely nowadays, as the industry has become preoccupied with teenage audiences and bathroom humor.

This spring, George Clooney flexes his comedic muscles. The year after playing a fixer in the bleak legal drama “Michael Clayton,” the actor stars in “Leatherheads,” a screwball comedy set in 1925. Opening April 4, the film is about an older football legend played by Mr. Clooney and a young college star played by John Krasinski (“The Office”) — both trying to win the heart of a young female journalist.

On April 25, Guantanamo Bay makes an unlikely appearance in a big-studio comedy; the military base, home to a controversial detention center, serves less as a point of outrage than as the movie’s central punch line. In “Harold & Kumar Escape from Guantanamo Bay,” two stoners (John Cho and Kal Penn) are mistaken for terrorists on a flight to Amsterdam and classified as “enemy combatants.” Also on April 25, “Baby Mama” scrambles up the formula of the modern pregnancy comedy. In the film — it’s the closing night feature for the Tribeca Film Festival, which opens on April 23 — Tina Fey plays a go-get-’em, single career woman who hires a surrogate mother (Amy Poehler) to carry her baby.

Fast-forward another week, and two surreal comedies open opposite each other on New York screens. On May 2, “Son of Rambow,” a hit at the 2007 Sundance Film Festival, tells the adorable story of two young boys who see the first “Rambo” film in 1982 England, and set about filming their own, amateur homage to the Hollywood blockbuster. On the same day, director Harmony Korine (“Gummo”) returns with the mind-bending “Mister Lonely.” It’s an an absurdist fantasy about a collective of impersonators in rural Scotland, a Michael Jackson wannabe rubbing shoulders with Marilyn Monroe, Charlie Chaplin shooting the breeze with Abraham Lincoln and Shirley Temple.

Even filmmaker Wong Kar Wai is embracing the whimsy of the season, with “My Blueberry Nights.” His long-awaited English-language debut, starring Norah Jones as a lovelorn woman who goes on a road trip across America in search of the answers to life’s many riddles, opens on April 4.

In May, two superhero films take a few steps back from the rawness we saw in “Batman Begins” and “Casino Royale.” On May 2, “Iron Man” stars Robert Downey Jr. as an inventor who creates an advanced suit of armor to fight a diabolical scientist. A week later, the Wachowski brothers return with “Speed Racer.” It stars Emile Hirsch as the young driver behind the wheel of the Mach 5, a speed-racing car almost as cool as those of last summer’s “Transformers” movie.

And finally, three screen legends are making their triumphant returns this season. Al Pacino, who’s been out of the spotlight for three years, appears in the real-time thriller “88 Minutes,” opening on April 18. Director Martin Scorsese follows up his Oscar-winning “The Departed” with a Rolling Stones concert documentary, “Shine a Light,” out on April 4. And Burt Reynolds is back on April 25 with the cardsharp thriller “Deal,” in which he first coaches — and then competes against — a young protégé in a high-stakes poker tournament.

ssnyder@nysun.com