|Relatives:||John Grayson (husband, deceased), Dick Grayson (son)|
|Voiced by:||Diane Pershing (uncredited)|
Mary Grayson was the mother of Dick Grayson.
In an attempt to convince Mr. Haley to pay "insurance", Tony Zucco sabotaged the trapeze. During the show, in front of the entire crowd and young Dick, John and Mary fell to their deaths when the line snapped.