A big Cougar at about an arms length, he was headed my way fast, I got lucky, bad day for him.
Big ole muley at about 25 feet, I was actually sitting and resting mid day, he walked up on me, heard a click, knew it was a hoof on a rock, there he was. Still one of my favorite looking MD.
Then there is a black tail doe I shot as a kid. I decided to see how close I could walk up to her while she fed in a meadow. Grass was fairly tall, 12-18", so she had her head buried eating some forb or what ever right at the ground level. She'd look up, I'd freeze, and so on. I finally decide to shoot her at about 20 feet. I can't find jack in the scope, too close. So I go from back of the fur to the front, hit air, swing back to what I know is the chest and bang flop. Promptly gut shot her, way too back, 150 gr. 30 caliber, about a 90-100lb. Deer, instant death and a smelly mess I'll never forget gutting.