What is "American Idol" alumnus Clay Aiken doing on "America's Next Top Model"?

When will Donna Martin be coming back to "90210"?

And will anybody be excited to see Nick Lachey in a "One Tree Hill" cameo?

The CW announced two months worth of guest stars on Wednesday (Feb. 25), attempting to draw viewers in when the network's biggest shows return with new episodes in March and April.

April will be reunion month on "90210" (which actually airs its first Tuesday 9 p.m. episode on March 31). The show's April 7 episode will be directed by Brandon Walsh himself, Jason Priestley, who will get to work with some old friends, as Jennie Garth and Anne Gillespie return as Kelly Taylor and Jackie Taylor.

One week later, on April 14, Tori Spelling's Donna Martin comes back to Beverly Hills, reuniting with Kelly Taylor on "90210." For some reason, that episode also features Diablo Cody guesting as herself. Spelling and Garth will also appear in the show's April 14 episode.

[If you can't get enough Spelling, she'll also be returning to "Smallville" as Linda Lake for a March 12 episode.]

"Gossip Girl" doesn't have quite the same nostalgia factor as "90210," but a number of familiar faces will be back, starting on March 16, with Sebastian Stan as Chuck Bass' nemesis Carter Baizen. Then, on April 20, Wallace Shawn will return as Blair Waldorf's new step-father.

Most exciting, though, Michelle Trachtenberg will be back as the positively wicked Georgina Sparks, with a four-episode "Gossip Girl" arc starting on April 27.

Want more CW guest stars? Nick Lachey plays the brother of a "Dancing with the Stars" champion on the April 27 episode of "One Tree Hill." Hill Harper  ("CSI: NY") plays Barack Obama's law school buddy and one of the stars of "CSI: NY" on the April 3 episode of "The Game." And "Spin City" veteran Michael Boatman starts a multi-episode arc on "The Game" starting on March 13.

It isn't just scripted shows getting a star infusion, though.

On the April 8 episode of "America's Next Top Model," the girls face an acting challenge and Clay Aiken -- of "Spamalot!" and "Scrubs" -- will be their guest judge. But does Clay have what it takes to teach the models to be fierce? One week later, Grammy winner Ciara surprises the models during a photo shoot.

 

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