John Marcus O'Sullivan (18 February 1881 – 9 February 1948) was an Irish Fine Gael politician who served as Minister for Education from 1926 to 1932 and Parliamentary Secretary to the Minister for Finance from 1924 to 1926.

[3] He was first elected to Dáil Éireann in 1923 as a Cumann na nGaedheal TD for the Kerry North constituency.

He was appointed to the Cabinet in 1926, serving under W. T. Cosgrave as Minister for Education.

In 1926, a report from the Second National Programme Conference was presented to him as the Minister for Education.

He accepted all proposals stated in the report to be recommended as a national curriculum.