Actress Kate Walsh is the tall, square-jawed redhead who plays Dr. Addison Montgomery in the ABC television series Private Practice, the 2007 spin-off of Grey's Anatomy. Walsh got her early acting experience in Chicago theater with the Piven Theatre Workshop. Her exposure to American audiences came with TV appearances in the late 1990s. She then had recurring roles in the early 2000s, in The Norm Show , The Drew Carey Show and HBO's The Mind of a Married Man. She first appeared on Grey's Anatomy in 2005, as the estranged spouse of Patrick Dempsey's character, Dr. Derek Shepherd. The popularity of Walsh and her character led to an expansion of her role in the series and she became a regular. Private Practice, a new series built around her character's move from Seattle to Los Angeles, debuted in the fall of 2007 with co-star Taye Diggs.