We report the discovery of four massive ( M > 0.8 M _ { \odot } ) ZZ Ceti white dwarfs , including an ultramassive 1.16 M _ { \odot } star . We obtained ground based , time-series photometry for thirteen white dwarfs from the Sloan Digital Sky Survey Data Release 7 and Data Release 10 whose atmospheric parameters place them within the ZZ Ceti instability strip . We detect mono-periodic pulsations in three of our targets ( J1053 , J1554 , and J2038 ) and identify three periods of pulsation in J0840 ( 173 , 327 , and 797 s ) . Fourier analysis of the remaining nine objects do not indicate variability above the 4 \langle { A } \rangle detection threshold . Our preliminary asteroseismic analysis of J0840 yields a stellar mass M = 1.14 \pm 0.01 M _ { \odot } , hydrogen and helium envelope masses of M _ { H } = 5.8 \times 10 ^ { -7 } M _ { \odot } and M _ { He } = 4.5 \times 10 ^ { -4 } M _ { \odot } , and an expected core crystallized mass ratio of 50-70 % . J1053 , J1554 , and J2038 have masses in the range 0.84 - 0.91 M _ { \odot } and are expected to have a CO core ; however , the core of J0840 could consist of highly crystallized CO or ONeMg given its high mass . These newly discovered massive pulsators represent a significant increase in the number of known ZZ Ceti white dwarfs with mass M > 0.85 M _ { \odot } , and detailed asteroseismic modeling of J0840 will allow for significant tests of crystallization theory in CO and ONeMg core white dwarfs .