It's Rodney the Ram.
Rodney isn't a terribly complicated ram. When he was young, he was a weak sheepling.. the runt of the litter, you might've called him. But through sheer hard work and willpower, he was able to grow into the powerful creature you see today. Rodney now makes his living as a personal trainer; it's easy to convince other people to pay good money for a trainer when they see you can benchpress a whole bus, after all. Despite his "modest" beginnings, that's not a word to describe Rodney himself-- he knows he's strong, he knows he looks good, and he's not afraid to flaunt it a little. Because of this, he's a sexually active ram, as well. A healthy sex life can be part of a good workout routine, too, you know? Rodney hasn't settled down with any one partner, yet.. not because he's afraid of commitment or a cheater or anything, but simply because he knows he's still young, and he hasn't met the right person. There's still plenty of time to enjoy life and meet new people.
As a result of growing up a runt himself, Rodney has a soft spot for the young, weaker patrons of the park. He likes to take the kids who aren't very strong under his wing, acting as sort of a big brother figure to them. (His own brothers and sisters were kind of assholes, so he figures a strong older role model would be a nice change of pace for some of these kids.) Stern, but only because he cares, Rodney is quick to scold youths who laze about all day, encouraging them to get up and exercise, instead. After all, they don't want to grow up at the bottom of the food chain, do they?