Vera Peterson (nee Kreitzer) is Norm's wife, who is an unseen character mentioned often in the series. It is revealed in the pilot episode, Give Me a Ring Sometime, that she knows that Norm hangs out at Cheers but doesn't care. Despite Norm's constant jokes about Vera, he is shown at times to actually deeply care for her, such as when she was fired by John Allen Hill.
Even though Vera is never directly seen throughout the series, there have been a handful of times she's been heard: Thanksgiving Orphans, It's a Wonderful Wife, No Rest for the Woody, Look Before You Sleep and Love Thy Neighbor. In all instances, Bernadette Birkett provided the voice of Vera Peterson. She is briefly onscreen at the end of Thanksgiving Orphans, with her face obscured by a pie thrown by Diane.
Of note is that Bernadette Birkett and George Wendt have been married since 1978 and remain so to date ! They have a daughter, a son, and two step-children.