Sarah Walker.

About Sarah Walker

Sarah Lisa Bartowski is the alias of one of the main characters of the television show Chuck on NBC. She is portrayed by Yvonne Strahovski and is one of two agents assigned by the NSA and CIA to protect Chuck Bartowski after he unwittingly downloads the secret government computer known as the Intersect into his brain. Throughout the series, she is Chuck's primary love interest and initially poses as Chuck's girlfriend to conceal their identities as spies from the public. In the Season 4 finale, "Chuck Versus the Cliffhanger", Chuck and Sarah were married, dismissed from government service, and given ownership of Volkoff Industries, with which they bought the Burbank Buy More and the secret Castle base thereunder. During the final three episodes of season 5, Sarah gets her memories suppressed due to a faulty Intersect upload, the signs of recovery from which are exhibited throughout the final episode. At an episode later in the series her real first name is known to be Sam, and a while later her real middle name is said to be Lisa.