I can think of twice. The first back in the 90's when I had a huge IA nontypical just suddenly appear in the middle of an all-dayer about 35-40 yards away. I wasn't going to shoot that far anyway, but I was so awed I forgot all about my camera hanging on the peg. This buck had it all, wide, massive, stickers all over, and I got the impression it had a double row of tines. When it walked away, I suddenly remembered my camera but it was too late. I can't even draw the antlers (and I usually can); honestly, I'd bet money it was over 200 inches
The second time was when I was in a pit blind disguised as a termite mound and a huge eland bull stood just 10-15 yards away, quartering slightly at me. Honestly, with a kill zone that big and at that range it should've been a give me. But I was psyched out by that animal's musculature and didn't take the shot, waiting on a broadside or quartering away angle which I did not get.