What is Columbo's first name?
It was never given in the show. When Columbo is asked what his first name is, he says "Lieutenant". On another occasion, he is asked if he has a first name, and Columbo says, "I do, but my wife is about the only one who uses it."
Have we ever seen Mrs. Columbo?
No. There have been several times when she was supposed to appear, but she never did. She was reportedly seen (off-camera) by other characters in some episodes, and we have seen Columbo talking to her on the phone. We have seen her car, and a picture of her sister, Ruth, but that's the closest we've ever come to seeing Mrs Columbo.