This guy at my job was saying mean things about me, but he is always staring at me

It could be that this guy is lashing out at you because you don't give him as much attention as he thinks you should be giving him, especially when you say that he gets you things at work and other small things. he obviously likes you but is having a hard time as he doesn't know how to ask you or approach the situation. maybe he doesn't feel comfortable going out with someone at work and is annoyed that he's attracted to you. maybe he thinks that the only way for him to get rid of this attraction towards you is to visualize you as someone he detests and loathes. I know, it's very immature and you've done nothing wrong. if I were you, just avoid him as much as possible and don't let him do you little favours at work. just avoid him altogether, like if you need to take the long way to get to the bathroom and it passes through his desk, I'd take the long way. hopefully by doing things like this, he'll catch on that you're avoiding him. if however, his actions escalate then you should go and speak to the Human Resources department and talk to them about it. It's called harassment at work. Hopefully it doesn't go that far, but just in case, I'd try to nip it in the bud.

If all he is doing is being mean/hateful towards you then he could just be staring at you because he dislikes you so much. I would definitely not interpret his staring as any sense of him being attracted to you. Just as humans are prone to not be able to turn away from the things they enjoy, they too are unable to turn away from those things that they dislike. It could be something else, but from him only staring I would not be lead to any other conclusion.