Bob

Age - 741 

Always on the top of every lewd monster leaderboard, Bob (who is a Bob, don’t ask) is probably the most perverted monster that exists in caves. He has the "ability" to grow boners whenever he wants. They are prized by some members of the community, but most of those people are just lonely and want to have some "fun," if you know what I mean. 

Bob is the father of countless children, though many don’t realize it. Each of his boners are loaded with his semen, and they are fully capable of working without being near a Bob. Surprisingly enough, all Bob’s semen is compatible with human eggs. 

MangaGamer