Ernest John Bartlett Allen (29 March 1884 – 16 June 1945) was a British socialist active in the United Kingdom and New Zealand.

He joined the Social Democratic Federation in 1900, and in May 1904 participated in the Provisional Committee which led to the founding in June of the Socialist Party of Great Britain.

During the first few years of its existence Allen was very active in the SPGB, speaking at both indoor and outdoor venues and writing for the Socialist Standard.

He spoke in Chicago with Malatesta in October 1908 and with Rudolf Rocker at the Charlotte Street Club in London the following month.

Despite his degree Allen did not have a professional career, working in the 1920s variously as an unskilled labourer, clerk and driver.