Former “Days of our Lives” siren <strong>Krista Allen</strong> (ex-Billie Reed) has had quite an impressive run since departing Salem in 1999 with roles on shows like “Mistresses,” “Baywatch,” “Hawaii Five-0” and “Melissa & Joey,” but her latest gig puts her back in the soap orbit — at least partially: She’ll be featured in an upcoming episode of ABC’s “Castle,” which stars former “One Life to Live” actor, <strong>Nathan Fillion </strong>(ex-Joey Buchanan)!