We present stellar explosion simulations of low mass evolved and high mass polytrope Population III stars. The lower mass evolved single and binary models of 10 and 16M⊙ are presented in a separate work in these proceedings (Lawlor 2005). It is found that the accreted model retains a larger mass and has a larger radius leading to a brighter supernova than the evolved single stars. Polytropes are used as presupernova stars to investigate possible pair instability explosions of massive stars. SN 2006gy is a possible candidate for such an explosion (see Smith in these proceedings). We find upper limits based on the light curve analysis with M<50M⊙, R<355R ⊙, 56Nimass<5M⊙, and energy <100×1051 from the R-Band data. Theoretical supernova light curves are presented at different redshifts with our model that comes closest to fitting SN 2006gy.