We have examined 40 NuSTAR light curves (LCs) of five TeV emitting high synchrotron peakedblazars: 1ES 0229+200, Mrk 421, Mrk 501, 1ES 1959+650 and PKS 2155−304. Four of the blazars showed intraday variability in the NuSTAR energy range of 3–79 keV. Using a structure function analysis we searched for intraday variability timescales in these LCs and found indications of several between 2.6 and 34.4 ks in five LCs of Mrk 421, and a timescale around 7.5 ks for one LC of Mrk 501. We also employed an auto correlation function analysis and found indications of very similar
timescales during those six observations as well as hints of timescales in four additional observations
of Mrk 421. The other three blazars’ LCs do not show any evidence for intraday variability timescales
shorter than the lengths of those observations; however, the data was both sparser, and noisier, for
them. The 22 LCs of Mrk 421 observed between July 2012 and April 2013 show that this source was in a quiescent state for an extended period of time and then underwent an unprecedented double peaked outburst while monitored on a daily basis during 10 – 16 April 2013. We briefly discuss models capable of explaining these blazar emissions.