| Alphonse Eugène Beau de Rochas | |
| Birth Date: | 1815 4, df=y |
| Birth Place: | Digne-les-Bains, Alpes-de-Haute-Provence |
| Death Place: | Vincennes |
| Nationality: | French |
| Known For: | Four-stroke internal-combustion engine |
| Occupation: | Engineer |
Alphonse Eugène Beau de Rochas (9 April 1815, Digne-les-Bains, Alpes-de-Haute-Provence – 27 March 1893, Vincennes) was a French engineer. He was the first to patent the four-stroke engine in 1862, but he did not build one and the idea was subsequently developed by Nicolaus Otto and other engineers.[1]