In the wild wich animal can walk right up to a deer that will not scare it?

I have seen a group of turkey followed by several deer on numerous occassions!

got this pic today.

Oh come on

I didn't even vote in this poll! It's a very loaded question, and the answer is complicated, at best! Are we talking noise? Sight? Smell?
Answers can vary from area to area, and day to day even!
Naturally, known preditors are going to be high on the list! Man, which is not on the poll, is at the very top of the list! Anything to do with man, is going to spook deer 99.99 percent of the time!
I've seen deer spook at squirrels, and small birds, and I've snuck up on deer while on horse-back! Go figure!

Here in my area the moose and the deer coenside very well.

Deer seem to hang behind turkeys here in Kentucky, so if you see one the other isn't far behind. I guess the deer use the turkey's superior sight in conjunction with their sense of smell. Hard combination to beat. Squirrels on the other hand are everywhere and are just as likely to bust you as they are deer. When the squirrels all start looking back in the same direction while they are feeding I can almost put money on the fact that deer are in the area. I have seen some coons and possumsaround persimmons and deer will move cautiously in to feed as well.

Them beeping squirels will start squaking and the deer will look at you
and get you busted.

squirrels and turkeys don't seem to spook deer too much.

Where's the armadillo? You forgot the armadillo!! I see them hanging out together in fields all the time. That would be my vote.