<P> Margaret `` Maggie '' Pierce , M.D. is a fictional character from the American television medical drama Grey 's Anatomy , which airs on the American Broadcasting Company ( ABC ) in the United States . The character was created by series producer Shonda Rhimes and is portrayed by actress Kelly McCreary from the tenth season 's penultimate episode onwards . It is revealed in the `` season ten finale '' , Maggie 's biological parents are Richard Webber ( James Pickens Jr . ) and Ellis Grey ( Kate Burton ) , making her Meredith 's half - sister . McCreary was upgraded to a series regular in the eleventh episode of the eleventh season . </P>
<P> Margaret `` Maggie '' Pierce , M.D. is a fictional character from the American television medical drama Grey 's Anatomy , which airs on the American Broadcasting Company ( ABC ) in the United States . The character was created by series producer Shonda Rhimes and is portrayed by actress Kelly McCreary from the tenth season 's penultimate episode onwards . It is revealed in the `` season ten finale '' , Maggie 's biological parents are Richard Webber ( James Pickens Jr . ) and Ellis Grey ( Kate Burton ) , making her Meredith 's half - sister . McCreary was upgraded to a series regular in the eleventh episode of the eleventh season . </P>
who plays meredith grey 's sister on grey 's anatomy
who plays meredith grey 's sister on grey 's anatomy
Kelly McCreary
Kelly McCreary