James Clark Gentles FRSE (18 March 1921 – 15 November 1997) was a Scottish mycologist and the first British person to specialise in fungal disease on the human body.

He attended school locally then went to Glasgow University studying Natural History.

In the Second World War, Gentles served in the Royal Air Force as a radar operator.

In 1947, Carl Hamilton Browning head-hunted Gentles to Head his new department investigating fungal diseases of the human body at Glasgow University.

On return to Browning in Glasgow, he was appointed to the Medical Research Council, his first task being to investigate ringworm in the feet of Scottish miners.