Different theories as to the origin, including a mere prank on 4chan, but it quickly became co-opted when certain people saw how easy it was to weaponize it when it jumped to FB and reddit.
Q isn't one person; the prevailing belief is that it's usually a team of puppet masters that have shifted over time.
Mike Flynn has been involved as one of the most recognizable names. Steve Bannon too. At the very least they have been part of the team coming up with the strategy to weaponize the cult.
But the one consistent, actually two consistent people are Jim Watkins (owner of 8kun, and a purveyor of porn, including child abuse) and his son, Ron.
Ron resigned from 8kun I think on Saturday.
But here's the scary part. Another name that has been bandied about as having been part of the team is recently in the news, with Trump appointing him as Chief of Staff of DoD:
Ezra Cohen-Watnick
Personally, I don't think it has mattered for a while who Q is. It all took on a life of its own with grifters on different levels, like MLM. They're gonna ride the "Dems are demonic pedophiles" schtick for a long time. They don't even pay attention to the Qdrops. But that network will probably be used (manipulated) again and again and again. And we see how easily they radicalized many of them.
I thought the news about Jim Watkins' involvement and him peddling child sexual abuse would be the thing that blew it up but it had already metastasized too much. At this point, they only believe what they want and say everything else is fake news.