Michele Angelo Besso (Riesbach, 25 May 1873 – Geneva, 15 March 1955) was a Swiss-Italian engineer who worked closely with Albert Einstein.

Einstein called Besso “the best sounding board in Europe” for scientific ideas.

[6] In Einstein's original paper on special relativity, he ended the paper by stating, “In conclusion, let me note that my friend and colleague M. Besso steadfastly stood by me in my work on the problem here discussed, and that I am indebted to him for many a valuable suggestion.”[7] Besso died in Geneva, aged 81.

In a letter of condolence to the Besso family, Albert Einstein wrote “Now he has preceded me a little in parting from this strange world, too.

For us believing physicists the distinction between past, present, and future only has the meaning of an illusion, though a persistent one.”[8] Einstein died one month and 3 days after his friend, on 18 April 1955.