Mumberthrax Flathead the Insignificant, the sixth king of the Flathead Dynasty, ruled the kingdom from Egreth Castle during the years 755~770 GUE. Historians note that Mumberthrax's reign was significant for exactly thirteen, and only thirteen, reasons. The first reason was his royal decree that made Double Fanucci the National Sport of Quendor. As for the other reasons, Boswell Barwell writes that "Mumberthrax's place in history was secured by the one thing at which Flatheads tended to excel: procreation." Mumberthrax was the father of the famed Twelve Flatheads.

Mumberthrax was perhaps the most extreme example of being affected by Duncanthrax’s propaganda that he was the most awesome king of all time, spending his entire life utterly convinced of his own unimportance, completely unwilling to perform any deed that would cause him to be remembered by history. Already, Mumberthrax had throughout his childhood been incessantly taunted and tormented by his uncle Timberthrax, and even the his own enigmatic father, Phloid. Perhaps embittered by the long wait for the throne, both Timberthrax and Phloid were not particularly nice individuals, and were constantly taking pains to make Mumberthrax clearly aware of how unbelievably insignificant he was in the grander scheme of things. After years of this torment, Mumberthrax becoming ingrained with one of the greatest inferiority complexes history has ever, and logically came to extend his own feeling of unimportance to include that of his dozen children. Convinced of his own irrelevance, Mumberthrax could see little reason to think that his son Dimwit would turn out much better.

Boswell Barwell, the official biographer of the Flatheads writes that “Mumberthrax's place in history was secured by the one thing at which Flatheads tended to excel: procreation.” In 723 GUE, Dimwit Flathead, the great-great-great-great grandson of King Duncanthranx, who would be alternately described as “a colorful figure” and “the most wretched ruler Quendor has ever seen,” was born to Prince Mumberthrax, great-great-grandson of Duncanthrax. Dimwit would be followed by eleven more eclectically distinguished siblings: a captain of industry, a military hero, a musical genius, a dauntless banker and financer, an inventor extraordinaire, an artist and scientist, a chronic widow, a poet, a seaman and explorer, a royal architect, and a legendary athlete. Each of these twelve amazing children would transform the kingdom. As these magnificent siblings grew in notoriety, as their vast achievements became legendary, they would become known as The Twelve Flatheads, and play a role in the most romanticized era of Zork’s history, the reign of Lord Dimwit Flathead.

John D. Flathead was the second child born to Mumberthrax in 725 GUE.
T.J. “Stonewall” Flathead was the third child born to Mumberthrax in 726 GUE.
Johann Sebastian Flathead was the fourth child born to Mumberthrax in 728 GUE.
J. Pierpont Flathead was the fifth child born to Mumberthrax in 730 GUE, followed later that year by his sixth, Thomas Alva Flathead.
Leonardo Flathead was the seventh child born to Mumberthrax in 731 GUE.
Lucrezia Flathead, the only sister to eleven aggressive brothers, was the eighth child born to Mumberthrax in 735 GUE.
Ralph Waldo Flathead, known as the Poet of the Empire, was the ninth child born to Mumberthrax in 737 GUE.
John Paul Flathead was the tenth child born to Mumberthrax in 738 GUE. From an early age, John Paul suffered from an inferiority complex derived from being the second “John” among the Flathead children. In his autobiography, Mumberthrax explains that when he named John Paul he “simply forgot about John D.” This complex made John Paul determined to become a world-famous seafaring adventurer.
Frank Lloyd Flathead was the eleventh child born to Mumberthrax in 741 GUE.
Often called the flattest of the Flatheads, Babe, the youngest of the Twelve Flatheads, was born to Mumberthrax with an aptitude for sport.

Since the birth of his first-born son, Mumberthrax had already been labeled the Not Terribly Important, and would be an old man by the time he claimed the crown. Becoming the sixth king of the Flathead Dynasty, Mumberthrax Flathead, also known as Mumberthrax the Insignificant, succeeded Phloid Flathead in 755 and ruled the kingdom from Egreth Castle until 770. With Dimwit already long since born and on his way to the throne of Quendor, what Mumberthrax did during his reign was so irrelevant that to even bother with trying to write a history of the next twenty years seems like a waste of effort. It has often been said that poor Mumberthrax spent fifteen years on the throne of Quendor and only managed to accomplish thirteen important things. What is usually lost in the chronological shuffle is the fact that of those thirteen important things, the first twelve had already long since been taken care of by the time Mumberthrax came to the throne. Scholars and fans of the Flathead family have taken great pains to avoid this sticky fact and point to the often forgotten.

It was during the reign of Mumberthrax when the famous Syovar met the beautiful and singularly talented Lorena of Mauldwood, a relative by marriage of a distant wing of the ruling family. Stricken with love for the first time in his young life, Syovar spent months sighing over the young countess from a distance before Mumberthrax himself caught wind of his young enchanter-knight's romantic obsession. The meddling monarch's order that the two be wed by the end of the week may be counted among the ‘169 Not Quite as Important Things’ that marked the fifteen years of Mumberthrax's reign.

As every student of history knows, the Twelve Flatheads were the greater part of the Thirteen Significant Accomplishments of King Mumberthrax the Insignificant. Historians note that Mumberthrax's reign was significant for exactly thirteen, and only thirteen, reasons. The thirteenth accomplishment was a royal decree that made Double Fanucci the National Sport of Quendor after almost a hundred years of growing popularity.  Invented by Zilbo III, the last king of the Entharion Dynasty, Double Fanucci had been an annual event since 691 GUE, and Mumberthrax’s Proclamation of 757 simply gave the sport official royal approval.

Frank Lloyd Flathead got his big break at the tender age of 17, when his father, King Mumberthrax, commissioned him to design a new wing for Castle Egreth. The resulting wing was breathtakingly impressive. As Frank Lloyd himself wrote, “the conjunction of space and time seems to interface in a pre-subjected instantiation of the underrepresented whole.” Frank Lloyd became, overnight, the hottest architect in the Kingdom. (The fact that the new wing of Egreth collapsed two years later, killing over 4,000 royal guests, was credited to a miscalculation on the stonemason’s part. He was summarily executed.)

When Mumberthrax felt death's icy hand in 770 GUE, his son, Dimwit Flathead, assumed the Quendoran throne.