No horse approaches me in pasture without my permission. Seriously. Taught the new boys this today when they were standing in front of the gate when I went up to it to get my "lower third in the rankings" gelding from his turnout today. I expect ALL horses to respect my bubble and get out of the way, no matter where I am, and the fact that I have nothing to do with the other horses actually makes it easier. They get told off (by the point of a whip if my body language and a rope aren't enough) once, again, and as many times as it takes until it sinks in. I don't settle for a begruding back-up, either. I expect them to MOVE OUT OF MY WAY, NOW. After a few times of that, and never giving them treats or attention, most of them just take a look at me and wander off.
Part of the reason is my own safety, but a large part of it is my horse's safety. He's not a dominant horse, so if other, more dominant horses are loitering near me or the gate, that can be a dangerous or anxious situation for both of us. The routine is now: I clear the gate area of the other horses, then once they've given me my space, he happily walks up and I let him through the gate or halter him and we're on our way. Took a little while, but as soon as he realized I was never chasing him off, only the others, he got smart and realized that as soon as he got behind me, he was 'protected.' If another horse comes up to mine to move him off while I am interacting with him, they get their little rear ends chased off post-haste. Ever watch one horse protect another from the herd in pasture? Same thing. They get it, and now I only have to repeat that message when there are newbies in the herd that don't know better yet.