Frank J. Lawless (10 October 1870 – 16 April 1922) was an Irish revolutionary and politician who served as a Sinn Féin Teachta Dála (TD) for Dublin North from 1919 to 1922.

Frank Lawless took part in the 1916 Easter Rising, being second-in-command under Thomas Ashe in the fight at Ashbourne, County Meath.

He was paroled to permit him to take part in the 1918 election, was present at the declaration at Balbriggan but returned to Usk prison on the same day.

Ashe was Frank Lawless's commanding officer, when the latter served with 4th section, Cork no.1 brigade during the war of independence.

A victory for the Irish volunteers, who defeated a superior number of RIC at the crossroads of Ballyannan on the Friday of Easter Week.