Dr. Astro

Dr. Astro is a character from Phineas and Ferb and is a minor antagonist in the first season of The Knights of the Multiverse. He is a member of the evil organization L.O.S.R., and as his name implies, he focuses on astrology & other outer space-related sciences. He is also frequent "rivals" with Dr. B.

Dr. B
Dr. B claims to be his rival, but Astro just sees him as a kid trying to prove himself.