"Grey's Anatomy" has been a successful drama TV series, given its long run of 11 seasons. Well, the drama isn't over. In the new season, Kate Burton will return to "Grey's Anatomy" to reprise her role as Ellis Grey.

Ellis Grey is a legendary surgeon in Grey Sloan Memorial Hospital. She is also Meredith and Margaret Pierce's mother. TVLine confirmed that she will be back in season 11 to help explain the backstory of Meredith's half-sister Margaret. Burton last appeared on the TV drama in Season 8.

Ellis Grey's return is a necessity for the storyline of Margaret, Ellis and Dr. Richard Webber's daughter. The first episode of season 11 will show what happened through a series of flashbacks.

Back in the season 10 finale, Dr. Webber and Margaret were talking and Margaret shared that she wants to be Yang's replacement. Margaret shared that she wants to work at Grey Sloan Memorial Hospital because this was where her birth mother worked before. It was then and there that Dr. Webber realized that he was talking to his daughter.

Was Margeret's inclusion in "Grey's Anatomy" on a whim? Apparently not. "That was one of the original pieces of story since the beginning with the Richard-Ellis dynamic, but it's been a piece of story since Season 4 when we talked about introducing her," show creator Shona Rhimes told TV Guide.

"Because we've all known about it for so long, it's always been layered in. It's not a thing where we're going in and backdating. It's literally always been layered into the story line. We can literally go back and pull out moments of the show and I'm excited to do so, and point out where it was talked about. It's not going to be so hard to do," she added.

"Grey's Anatomy" Season 11 returns on ABC on September 25 at 8 p.m.