Dee Dee (great-niece)
Fergle O'Reilly (nephew)
|First Appearance||If Memory Serves|
|Voiced By||Kath Soucie|
Not much is known about her, but she seems to be a very kindly old woman who was eager to see the newest member of her family.
Shortly after Dexter's birth, she paid a visit to the family to see him, however the infant Dexter was more than horrified by Dextamina's ghastly appearance and immediately began to cry.
After Mandark took Dexter's Memory Scanner/Viewer Machine, he hoped to find out Dexter's secret by seeing into his past, but instead he ends up reliving all of Dexter's infant/toddler memories, as well as the horrendous sight of Dextamina's face.