HR diagram of massive and supermassive stars at zero metallicity at accretion rates of 10⁻⁶ M_⊙ yr⁻¹ to 10³ M_⊙ yr⁻¹. The background colors indicate radii in units of solar radius. The blue line represents the Z = 0 ZAMS track with red dots marking masses in solar units. The tracks are labelled by accretion rate in black. The black dots indicate the end point of computation which corresponds to end of core Silicon burning for accretion rates up to 10⁻² M_⊙ yr⁻¹ and the onset of GR instability for higher accretion rates.