There was a guy who worked for another company in my office building. I got the lift with him a few times and just couldn't wait to get out. I don't know why, he just made me feel so uneasy. He's was not unpleasant, said hello when we ( colleagues) bumped into him, smiled when it's appropriate to smile, exchanged appropriate small talk, but he just made me feel cold and uneasy. I thought it was just me. Didn't mention it to colleagues because I didn't want them to think I am "woo" or weird. And, as far as we know, he's was just a neighboring office worker.
One evening there were building drinks on the roof terrace, most of my office where there, he was there with colleagues and people from a few other companies. Most people had headed off. He was still there and I was still there with another female colleague, must have been around 20-25 people left. All good. Then, two of our senior male colleagues came back, they'd left together to head home and been gone for about half an hour. We asked why they'd come back and they made up some bullshit about having forgotten stuff in the office. They waited until I and female colleague wanted to leave and walked us to the taxi station then left again. Strange, but nothing was said.
About a year later we were having drinks all together and had had a bit to drink, we were talking about our building and the fact that this guys company had moved out came up. The male colleagues who'd came back to fetch us that evening mentioned that they were both glad he'd left and I asked why - their reply was "no idea but we talked about him when we left the roof party and decided to come back to make sure you two were okay, because his vibes were off". Conversation went on and another colleague admitted she'd nearly wet herself with fear when she bumped into him in the shared building kitchen one morning.
Up until that point no-one had ever mentioned him. At that point we of course googled the shit out of him and found absolutely nothing untoward.
Is he evil or not ? No idea. But he gave off serious "malaise".