Baron Brain, of Eynsham in the County of Oxford, is a title in the Peerage of the United Kingdom.

[2] It was created on 26 January 1962 for the physician and neurologist Sir Russell Brain, 1st Baronet.

He had already been created a Baronet, of Reading in the County of Berkshire, on 29 June 1954.

[3] As of 2014[update] the titles are held by his youngest son, the third Baron, who succeeded in that year.

He is a retired physician and a former professor of medicine at McMaster University, Canada.