I posted a pic in the Case thread in the Sticky section. Should be on the last page or two. That's a Verus case and is what I have my S6 in right now. Never mind, somehow I missed the holster part.
Not sure if this is the type of holster you are looking for or not, but I've been a fan of Monaco leather belt clips/holsters. I originally purchased this for the old HTC Evo LTE, and also used with my M7. It's not an exact fit for the S6 height wise, but width wise, it holds the phone tight enough to not fall out. I say its not an exact fit because its not quite tall enough to cover the entire phone, but it only sticks out ~1/4" at the top, which was close enough for me:
The BlackBerry Z30 leather holster is a quality holster worth a look. I used it for my S5 and it was an excellent fit. I don't have access to it anymore but Im sure it will fit the S6.
Can be found heavily discounted now at places like Walmart, etc...