Actually, I think the smallest .45s in an Auto are the M1911s like this one.
There are some deringer types in .45, but that isn't what your looking for.
I have a Kimber, I never tried any of the smaller .45s before and bought this one on impulse without research. As it turns out it looks like it's a fine gun, and I think the Colts make some good guns too, I wouldn't be afraid of buying a Defender. But you don't need anything this big to get the job done. I also have a SIG P238 like like some of the others here and I would carry it first before the Kimber because, it's easier to carry.
Notice any similarities
I don't intend to use it to scare someone off. I will carry it in case I need it. If the day comes and I need it, I will wait until I must and then I will pull it out and use it. I will not pull it and then see if I have to use it. It's like a smaurai sword, you pull it you can't put it back till it tastes blood. Therefore, knowing and believing this I will not pull it unless I know I must kill someone, not for flash.