The horse is being ridden by Marcus Aurelius. In fact, that is a statue in the Campidoglio, Rome. However, it is a replica statue made in 1981 when the second century original was removed for restoration (and presumably placed in a museum).
Interestingly, this is the only intact surviving statue of a pre-Christian Roman emperor. That's because the medieval Christians mistakenly thought it portrayed Constantine. Otherwise, they would have melted it, because that's how they roll(ed).
All coin images in Daniel's Coin Zoo are from my personal collection. I collect, research, and personally photograph every coin displayed on this site. PLEASE do not take my images without permission. If you would like to use any coin image you see, just ask me. Thank you.