I've read quite a few articles with fan theories of who Peter Quills father is. While we may have to wait over two years to finally learn the truth in "Guardians of the Galaxy 2." We can definitely deduce our way and eliminate contenders.
The following are fan theories that don't hold true.
Yondu, the captain of a bunch of space pirates is not even close to being possible. For one thing he calls Peter's dad a "Jackass." Furthermore, Nova Prime reveals that Peter’s old man is of an unknown ancient race.
Again, this guy doesn't seem to fit the theme of ancient or hardly seen alien race. Also, if he paid Yondu to bring him Peter back why didn't he show any emotion when he met his son? Because it isn't his son?
While Adam seems like a possible candidate. It really doesn't make sense. For one though his DNA would have given Peter the ability to hold on to the stone his story would have to be revamped like crazy for it to even come close to making sense and while changing an obscure character doesn't upset the audience, changing one as well known as Adam would upset the comic book community. Also, why wouldn't he just get his kid himself?
Gunn has clearly stated that he will be deviating from this. Spartax will not be Peter's father. Besides, that guy doesn't seem angelic at all.
While it would have been very Star Wars to make Ronan Peter's father it just doesn't add up. Jondu never mentions knowing him and though the Kree are an ancient race Nova prime deals with them on a daily basis.
Just how? Well really all I have to say is that Nova Prime said it was something ancient that they hadn't seen in a very long time. Everyone knows of Thanos. Besides, Thanos has a son that betrays him, Thane. Thanos also doesn't seem like the type to hire Yondu to get his kid for him. Also, what is angelic about this guy? Or anyone else on this list?
Now to the possible fathers of that legendary space outlaw we have come to know and love. The following two characters are the only one's that make sense to me as defined by the clues given to us from the first film.
Ancient alien race.
Knows Yondu and is called a Jackass.
No, not the smash bros star. Eros, aka Starfox, is a casual ally to The Avengers and one of the Eternals of Titan—he also happens to be Thanos’ brother. The Eternals are a different branch of humans fabricated by the Celestials—who are the original wielders of the Infinity Stones. Meredith Quill’s dying words of Peter’s dad as an “angel” fit the bill since Starfox’s powers include sex appeal (or “psychic control of the emotions of others'').
Starfox hired Yondu to bring him Peter out of fear that Thanos would hurt his kid. Thanos doesn't play well with family. Yondu calling him a jackass fits...as Starfox is kind of a weird rapey like character. But this might account for Peter's pelvic sorcery. Also, the name Starfox could have led to the moniker Star Lord.
Starhawk is a complex character to say the least. He is a gender fluid human possessed by a hawk alien deity who likes to play god with space and time. I won't go much more into his story because if Gunn uses this guy he surely will revamp it. A member of the original Guardians of the Galaxy and therefore the best candidate to be Peter's dad. Yondu is also a member of the original team. I'm sure Gunn plans on using all four original members in the MCU even if they are completely different from their comic book counter parts. They will most likely also know each other which makes sense and gives the "jackass" line more weight.
Also, Starhawk can radiate bright light and manipulate it. A light crown (comparable to a halo) and light wings (angel wings) make him easily mistakable as an “angel” by an earth gal like Meredith Quill. Gunn will most likely find a way to tie Starhawk’s origins back to the Eternals or the Celestials in order to explain Starlord's ancient alien DNA.
And again a name like Starhawk could easily have led to the pet name Star Lord.