I've been taking it easy with my walking routine and Pokemon Go playing this week, but this morning I saw something pop up in my “nearby” indicator that I've never seen before: a wild Tyranitar! I don't know if this is just rare or if this is a new possibility as part of the Johto festival, but it turned my morning from a routine effort to his some gyms and stops while stretching my legs into a little mini-adventure. I was pretty nervous that it would de-spawn while I walked from where I was to the stop where it appeared (a mural painted on a building), but it was still there when I got there.
I tapped on it to go to the catch screen the instant after I took that last screenshot, but then I walked around the corner of the building so I could take an AR photo with the mural in the background, and then I switched back to non-AR mode to actually try to catch it.
It took quite a few tries (with golden razzberries and ultra balls) but I finally got it. It may not have the best IVs, but catching it was still a fun experience. Part of the reason I play this game is to help me stick to a routine where I get some exercise, but it's also nice when exciting and unexpected things happen, like the opportunity to capture a powerful pokemon in the wild.