Nicholas Henry Darnell (April 20, 1807 – July 16, 1885) was an American politician in Tennessee and Texas. He was the only person to serve as Speaker of the House of the Republic of Texas House of Representatives and the State of Texas House of Representatives. He was a member of the Tennessee General Assembly prior to his move to Texas, and during the Civil War raised and led the 18th Texas Cavalry Regiment, which was also known by the name of “Darnell's Regiment.”