Summer Glau is on her way to Seattle Grace.

The actress - best known for sci-fi roles on programs such as Dollhouse, The Cape and Alphas - will guest star on an upcoming episode of Grey's Anatomy. In what capacity? Creator Shonda Rhimes did not say, simply Tweeting that the actress was at a "table read" today.

We'll report more on the character when news breaks.

Matt Richenthal is the Editor in Chief of TV Fanatic. Follow him on Twitter and on Google+.