Carrie Fisher did very little voice work in video games in her long career in acting. Surprisingly, she only voiced Princess Leia in one Star Wars game (Lego Star Wars: The Force Awakens)! Her only other publicized role was a small cameo on Bethesda's Dishonored in which she has a couple lines via intercom that are unlocked via Easter Egg!

According to Glixel, you have the kill the propaganda officer in the Dunwall tower in the mission "Return To The Tower". If you do you'll hear Fisher's voice later in the game via intercom...

Pretty cool right? I'm still shocked Fisher only rarely did voice acting for video games! Then again, the only Star Wars actor who regularly does voice work period is Mark Hamill. I'm dying to find this Easter Egg!