Robert Collier, 2nd BaronMonkswell (26 January, 1845-22 December, 1909), was a British Liberal politician.
Monkswell was the eldest son of Robert Porrett Collier, 1st BaronMonkswell and his wife Isabella, daughter of William Rose.
He entered the House of Lords on his father's death in 1886, and later served in the Liberal administrations of William Gladstone and Lord Rosebery as a government whip from 1892 to 1895 and as Under-Secretary of State for War in 1895.