At this year's Comic Con, Molly Quinn, "Nathan Fillion's daughter" on the show Castle (which I love btw) came cosplayed as his character on Firefly, Captain "Mal" Reynolds :
Awww :)
Here's one more:
Enjoy part of the Castle panel when the crew came on stage:
Stana Katic couldn't attend this cause she was on the far other side at the Batman: Arkham City panel :P
