One guy particularly stands out, he joined the team and started off on a solo run with a couple of projects a few others were involved in. A few weeks later I asked him if he'd setup any meetings with the team to get context and, you know, say hello and his response was "why should I do that, can't they read my PRs?". Classic.
Another one was the very loudly self-diagnosed neurodiverse girl, who seemed to just use it as cover for being a total jerk. Eventually she had to be managed out, as she tipped the scale between doing good work and tolerance of odd behaviors too far - screaming in meetings, histrionics and stuff you'd expect more of someone living on a street corner.