Jaimie Alexander, born March 12, 1984, is an American actress. She is known for portraying Jessi on the TV series Kyle XY and Lady Sif in the Marvel Cinematic Universe. From 2015 until 2020, she starred in the NBC series Blindspot. In 2015, Alexander began starring as Jane Doe in the NBC series Blindspot. She made an uncredited cameo appearance as Sif in the TV series Loki in June 2021 and voiced the character in the TV series What If…?. She is set to reprise the role again in the upcoming film Thor: Love and Thunder.