Following the news that it's been picked up for a full season, Castle has announced a big guest-starring role.

Sources confirm to Michael Ausiello that Alyssa Milano will appear in early 2010 as a former love interest of Nathan Fillion’s title character.

On the installment titled “A Rose for Everafter," Castle reconnects with Milano's Kyra on her wedding day. Chemistry still exists between the exes, which Beckett picks up on, creating a little love triangle.

Milano was most recently seen on TV for 10 episodes of My Name Is Earl.

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