Although the current roster of the Guardians of the Galaxy (Star Lord, Gamora, Drax, Groot, Rocket) is taken from their current incarnation in the comics, Yondu (a Ravager captain in the MCU) is based on a character from the first Guardians of the Galaxy, from what is now called Earth-691.
Yondu is not the only Ravager captain; there were a number of other captains. There is one post-credit scene where a group of these captains were gathered together in a way very reminiscent of the Guardians themselves, implying that these characters being together was significant.
Do we know who these characters were, or at least who they were based on, and if there's any deeper meaning behind their appearance?