Who led the revolution against the Czars of Russia?

Lenin ended up taking charge.

There were two Russian Revolutions in 1917. The first, the February Revolution was not led by anyone. It began as a spontaneous demonstration by some women who were complaining about having to wait in line in the cold for hours to get bread. Eventually more and more people came into the streets demonstrating about other problems. The disturbances grew and spread to other cities. Tsar Nicholas II could not get the police or military forces to restore order and his ministers convinced him he had to abdicate to stop the rioting so he did. The Provisional Government under Prince Georgy Lvov then took over, but Lvov had not started or led the revolution. It just happened.

In the second revolution, the October Revolution, Vladimir Lenin planned and staged what was actually a military coup by his Bolshevik followers agaisnt Russia's Provisional Government by that time under Alexander Kerensky. It was not really a true "revolution" in the usual sense of the Word.