Sarah Louise Christine Chalke ( born August 27 , 1976 ) is a Canadian-American actress most famous for her role as Elliot Reid on Scrubs and Becky Conner on Roseanne . Sarah Chalke ( ; born August 27 , 1976 ) is a Canadian actress known for portraying Dr. Elliot Reid on the NBC\/ABC comedy Scrubs , `` Second Becky '' Conner Healy on Roseanne , and Stella Zinman in the CBS sitcom How I Met Your Mother .