[User23]

Dijkstra co-created a rather influential language called Algol 60[1]. It and its immediate descendants are still used in scholarly CS work because it's so good for clearly describing algorithms. Past that, the influence of Algol 60 on virtually all modern programming languages is hard to overstate.

[1] https://en.wikipedia.org/wiki/ALGOL_60

[AnimalMuppet]

Well, he co-authored a compiler. From what your link says, he wasn't part of the committee that created the language.