Which famous Muslim leader staunchly opposed the Two-nation theory?

Khan Abdul Ghaffar Khan

According to the ‘two-nation theory’ advanced by the Muslim League, India consisted of not one but two ‘people’, Hindus and Muslims. That is why it demanded Pakistan, a separate country for Muslims.
This theory fueled the demand for a separate Muslim-majority state.

Khan Abdul Gaffar Khan, the undisputed leader of the North Western Frontier Province and known as ‘Frontier Gandhi’, was staunchly opposed to the two-nation theory.