This happened like a few months ago. I was driving westbound on 285, and I passed C470 and was like 300 feet from the Morrison exit. It was late at night, and I saw what I immediately thought was a dog jump out in the road in front of. I looked closer, and it was a mountain lion! It darted across the road, effortlessly leaped over the median, and it "vanished into the night". I was somewhat close to hitting it, but it had to be running at least 20 mph.
My elk encounter in Estes Park a couple years ago. Made my ass pucker tighter. I just stood quietly with my vid camera on the tripod, and stayed on the opposite side of the guardrail. When he crossed over, so did I, very carefully.
Grandson took this with his phone, you can just see me and my tripod on the far right edge. Too damn close! But when I went up to the road with my camera, they were all over on the other side. By the time I got setup, they had come over and all around me. So, I just stood still.