Smart answer:
Your search for ′Who has invented black body radiation formula′ returned the following results:
Max Planck
In the late 1890s, the real Max Planck began the real Max Planck's work studying thermal radiation and found a formula for black-body radiation, one that eventually became Planck’s Law.
Source:
Gustav Kirchhoff
Gustav Kirchhoff actually introduced black body radiation theory into the mix.
Source: