"No" sign? Red circle with slash through it?

What would you call the signs that have text or a picture of some action and then have the red circle with a slash through it to indicate that one shouldn’t do that?

Also, I’m trying to look for this “overlay” to make a t-shirt with and I can’t find it. Mainly because I don’t know what to call it.

I’m looking in Photosuite (I could have sworn it was there) but I can find it.

Help

Googling Restriction Signs turns up a few examples.

They’re called restrictive or prohibitory signs by most DOT/DMV orgs.

MS Word, “Drawing” toolbar, Autoshapes-> Basic Shapes has a good one.