Paul Graham inspired the creation of Redis
PG was also involved in the inception of Reddit: It was PG who gave Alexis and Steve the idea to make something like reddit, and also gave them the tagline "the front page of the internet".[0]
PG had vetoed their initial idea to create a food-delivery app and then called them back and asked them to come up with something new.
[0]: https://www.youtube.com/watch?v=5rZ8f3Bx6Po