Mauler has been GameStop's CEO for three months.
GameStop has been struggling to excite investors after posting disappointing earnings. Right after it announced the appointment of Mauler, it fired Tony Bartel, COO, and Michael Hogan, an executive vice president.
According to the company, Mauler resigned for personal reasons.
The company announced that Daniel DeMatteo, the co-founder of GameStop, would take over the role until the board can find a permanent CEO.
GameStop's shares plummeted nearly 2% when the announcement was made. A GameStop spokesman said DeMatteo was not available for an interview.