Nicolás Romero (born in Nopala, Hidalgo, 6 December 1827; died in Mexico City, 11 March 1865) was a Mexican military figure.
He had agricultural and textile businesses in what is the modern-day state of Hidalgo. Upon the outbreak of the Reform War in 1858, he jointed the Liberal forces under Aureliano Rivera.
When Napoleonic France invaded in 1861, he engaged the invaders in guerrilla warfare, fighting in the states of México, Guerrero, Querétaro and Michoacán under Gen. Vicente Riva Palacio; there, his exploits earned him the nom de guerre León de la Montaña ("mountain lion"). He was captured by the enemy in Papazindán, Michoacán, from where he was taken to Mexico City and executed.
Ciudad Nicolás Romero in the State of México and Tiquicheo de Nicolás Romero in Michoacán bear his name.