Acker will appear in at least one episode of the ABC series as Audrey, the famous cellist first mentioned in Marvel's The Avengers as being the love of Phil Coulson's (Clark Gregg) life. A talented musician turning heads in Portland,tv & movies online, Audrey believes Coulson to be dead and has no idea that he's guarding her from a distance as a super-powered threat from her past re-emerges.

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The cellist, who had remained nameless until now, was mentioned earlier this season when Raina (Ruth Negga) goaded Coulson by saying his former long-distance lover had cried for days after his death.

Acker's casting marks a reunion between the actress and Gregg, who shared the screen in S.H.I.E.L.D. executive producer Joss Whedon's Much Ado About Nothing adaptation. Currently starring on Person of Interest, Acker is also well known for her roles on Whedon's Angel and Dollhouse, where she worked with S.H.I.E.L.D. bosses Jed Whedonand Maurissa Tancharoen. Her credits also include Once Upon a Time, The Good Wifeand Alias.

Acker will appear in an episode slated to air Tuesday, April 22. Are you excited to see her on Agents of S.H.I.E.L.D.?

Marvel's Agents of S.H.I.E.L.D. returns Tuesday, April 1 at 8/7c on ABC.