King Koopa's mother
From the Super Mario Wiki
“Koopums, go sit in the corner for six days!”
King Koopa's mother (alternatively known as Bowser's mother) is the mother of King Koopa, who she appears to be somewhat disappointed in and continously dots on; King Koopa's mother is portrayed as being loudmouthed and overbearing, and is also hinted at being somewhat of a glutton. King Koopa constantly refers to her as Mama, while she calls King Koopa, Koopums.
In The Super Mario Bros. Super Show! episode "Do You Princess Toadstool Take This Koopa...?", King Koopa, unable to think of any friends to invite to his wedding to Princess Toadstool, who he had blackmailed into marrying him, had Mouser invite his mother, who he stated would come for the cake.
Having apparently received Mouser's invitation, King Koopa's mother arrived at her son's castle as King Koopa was instructing his Koopa Troopa band to play better. Immediately showing praise for her son at having finally found a wife to settle down with, King Koopa's mother, upon seeing Princess Toadstool, proclaimed that after Princess Toadstool and her son were married, they would honeymoon with her in the foulest, smelliest swamp in seven worlds. This news caused Princess Toadstool to begin sobbing, which King Koopa's mother misinterpreted as Princess Toadstool being overcome with joy.
When Princess Toadstool and King Koopa's wedding was about to begin, King Koopa's mother noticed that her son wasn't dressed for the occasion, and immediately sent him away to get dressed. As King Koopa put on his wedding jacket and pants, which were earlier ruined and recently repaired by Mouser, his mother evidently became impatient and shrieked for her son to hurry; the sound of his mother's voice prompted King Koopa and Mouser to rush to the wedding, not noticing that King Koopa had left behind his Magic Scepter, which Mario managed to claim.
Before Princess Toadstool could say "I do" to King Koopa during the wedding, Super Mario, Super Luigi and Toad appeared to interrupt it with a hail of fireballs. As the various attending Koopa Troopas and Goombas went into a frenzied panic, King Koopa's mother seemingly managed to avoid the chaos and the collapse of the wedding cake. After things died down and Princess Toadstool, after having learned that King Koopa had changed all the Mushroom People into stone once again after he freed them, broke off her marriage to King Koopa, his mother voiced her outrage at her son. Hitting King Koopa on the head with a drum, his mother yelled that she had to tell all their relatives that King Koopa was still a bachelor before telling King Koopa to sit in the corner for six days, an order which caused King Koopa to faint.
King Koopa's mother is also mentioned in one of the Dear Princess Toadstool segments of the Nintendo Comics System series. In this segment, Koopa has written to Princess Toadstool asking for her opinion on his mother's advice that he should finish high school before continuing his plots to take over Mushroomland. Toadstool disagrees that a high school diploma is needed for world conquest, but does support his mother's opinion, citing that Koopa may want a real job someday.
Bowser's father is another non-game character who could have been married to King Koopa's mother. Poopa La Koopa is her implied father, as he is Bowser's grandfather. Alternatively, Poopa La Koopa could also be the father of Bowser's Father.