She first caught my attention during the first season of Nip/Tuck. Kate played a character named Vanessa, who started out dating Matt Macnamra, until we find out a couple episodes later, she is in love with another woman. And the other woman was none other than Sophia Bush. Her portrayl of a lesbian was very convincing and heartbreaking and I think she pulled it off wonderfully.
I also loved her in Brokeback Mountain. She didn't have a large part, but the times she was on screen were in my opinion, magical. She gave such depth and vulnerbility to her character, and I was just even more amazed by her. The character she played was Alma jr, daughter of Ennis (The late great Heath Ledger) and Alma (played by Michelle Williams) I think she really played well off of Heath, and held her own quite nicely.
I could write more about her, but I think I'd be bordering on obsessive lol. :] And just another photo of her, because why the hell not??