Mrs. McHenry was the wife of Anthony McHenry and the mother of Tony in It's Walky!. She never appeared in the strip itself, but her death was referenced repeatedly throughout the strip's run.
The particulars of her demise were never fully explained, but it was heavily hinted at that the Head Alien manipulated Tony into killing her in a particularly gruesome manner. However, Tony later confided the details behind Mrs. McHenry's death to Sal Walkerton, who was disgusted enough to use it as justification to kill him during the Year Zero incident.