Martin Luther and John Calvin were leaders of distinct denominations of what religious movement in the sixteenth century?

Answer is Protestantism.

Explanation:

Protestantism is known to be formed or established through 16th century reformation. It was believed to have started in 1517 in Germany by Martin Luther.

Protestantism comprised of other churches that do not share the same practice with Catholic, Anglican, Baptist or Eastern churches.

They are different from those churches mentioned above in many ways, but especially, because there is no structural unity and central human authority.

That is the reason why, they are diverse and more divided theologically when compared with the roman catholic church.