10: Jay Leno
No surprise here as Jay Leno has an impressive motorcycle collection to go with the rest of his automotive collection. In fact, he has more than just a collection, he has a working garage that people can actually visit. He has somewhere around 100 motorcycles in his collection, and that number is constantly expanding (via Go Rollick).
Most notable in the collection is the 1931 Henderson Four, a very rare motorcycle. There is also the Y2K, which is a rocket powered bike that Leno has pulled out of the garage a few times. His motorcycle collection is extensive and varied, making it unique to say the least.