Greys Anatomy - Season - 12

: This season marked the final regular appearance of Sara Ramirez as Callie Torres. Reception & Ratings

: Martin Henderson joined the cast as Dr. Nathan Riggs, whose arrival triggers a dark history for Owen Hunt involving his missing sister. Greys Anatomy - Season 12

: Jason George (Ben Warren) was promoted to a series regular. Giacomo Gianniotti (Andrew DeLuca) also became a regular mid-season. : This season marked the final regular appearance

: The couple's marriage collapses, leading to a divorce. However, they discover April is pregnant shortly before signing the papers. : Jason George (Ben Warren) was promoted to a series regular

: A bitter custody battle over their daughter, Sofia, ensues when Callie plans to move to New York with Penny.

: Miranda Bailey successfully campaigns to become the hospital’s first female Chief of Surgery .

: Tension peaks when Callie’s new girlfriend, Penny, is revealed to be one of the doctors who failed to save Derek. Penny eventually joins the hospital as a resident, causing friction with Meredith and Amelia. Relationship Turmoil :