Linda Edna Cardellini is an American actress. She is known for her roles as Lindsay Weir on Freaks and Geeks, Samantha Taggart on ER, Velma Dinkley in the live-action Scooby-Doo feature films, Sylvia Rosen, a neighbor of Don Draper's on the AMC drama series Mad Men, Meg Rayburn on the Netflix original series Bloodline, Cassie in Brokeback Mountain, and Laura Barton in Avengers: Age of Ultron.