The first official LGBT character in the Star Wars universe is Moff Delian Mors, a character in Paul S. Kemp's upcoming Star Wars: Lords of the Sith novel.
From publisher Random House:
"Moff Delian Mors is a supporting character in Star Wars: Lords of the Sith. She was a promising officer of the Empire, who was assigned to an undesirable post at the far end of the galaxy. At nearly the same point in her life, her wife was killed in a transport accident, and the weight of these burdens led to Delian becoming lax in her duties, and left her personal life in disarray. The events of Star Wars: Lords of the Sith occur a few years after her loss."
Jasmine Garsd at NPR's The Two Way has more. The novel is scheduled for release on April 28, 2015.