Using patterns in the oscillation frequencies of a white dwarf observed by K2 , we have measured the fastest rotation rate ( 1.13 \pm 0.02 hr ) of any isolated pulsating white dwarf known to date . Balmer-line fits to follow-up spectroscopy from the SOAR telescope show that the star ( SDSSJ0837+1856 , EPIC 211914185 ) is a 13 { , } 590 \pm 340 K , 0.87 \pm 0.03 M _ { \odot } white dwarf . This is the highest mass measured for any pulsating white dwarf with known rotation , suggesting a possible link between high mass and fast rotation . If it is the product of single-star evolution , its progenitor was a roughly 4.0 M _ { \odot } main-sequence B star ; we know very little about the angular momentum evolution of such intermediate-mass stars . We explore the possibility that this rapidly rotating white dwarf is the byproduct of a binary merger , which we conclude is unlikely given the pulsation periods observed .