This is funny, cos I saw this stated somewhere on HN the other day, was totally amazed he'd done both, went and checked, and found out it was untrue - I think! Someone correct me please if I'm confused.
Calvin Rose made Janet https://github.com/bakpakin and https://bakpakin.com/
Phil Hagelberg made Fennel https://git.sr.ht/~technomancy/fennel and https://technomancy.us/colophon
It's complicated; Calvin Rose was the original creator of Fennel ("fnl"), but I understand it was just a little side project that he made over the course of a week or so in college. Phil Hagelberg found the project years later and thought it was cool, took over as its maintainer, and basically turned it into the Fennel you know today. So it's like, kind of, I dunno, both things are kinda true.
That's even more funny in the end, I thought GP was referring to Phil Hagelberg as creator of both, but they were referring to Calvin Rose as creator of both. Oops. Mystery solved.
Anyway - Fennel and Janet look very interesting, and a large thank you to everyone involved!