That's ancient King Gentius riding the horse. He was the last king of Ardiaean, a state of Illyria, and ruled from 181-168 BCE.
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.