Who's This? The man who makes funny animals.
How you could have heard of him: If people know him at all, it's because of his appearances on The Brave and the Bold animated series (where he certainly belongs, if anywhere). He did apply for JLI membership in the New52, but was rejected.
Example story: Showcase #66 (January-February 1967) "The Birth of B'Wana Beast" by Bob Haney, Mike Sekowsky and George Roussos
...Let's have an aside at this point to talk about whether or not the B'Wana Beast strip is racist or not. Artist Mike Sekowski apparently thought so because he reportedly refused to draw any more after the second issue on those grounds. If it is, at this point (p.4), it's that 1) it's going to have a White Messiah hero, and 2) Africa is "generic", with what the uneducated and untraveled reader might expect from the continent. The proof is that you'd expect the Zambesi people and preserve to be close to the Zambesi River, but if it is, there's no way it's in spitting distance of Mount Kilimanjaro as pictured here. Africa as a tiny island where everything you know is close. We're in Jumanji. End aside...
The issue actually ends on a text piece entitled "B'Wana Beast's Real Africa", which takes some balls, honestly. Its education content includes the fact that it's the largest continent, despite it seeming extremely small in the story. Writing about a place you've never been to is a touchy proposition, and I'm sure Kenboya scolding his people about their superstitions - when there's a mystically-powered superhero RIGHT THERE - would have gotten more than insensitive over time. "B'Wana", a term meaning "Master", here means he's called "Beast Master" probably, but since it has strong colonial connotations, it too is a problem for current-day readers. Somehow, it didn't stop him showing up a couple time on a current-day cartoon. Maybe it works because he's so silly there. But look, who doesn't like a cool animal mash-up?
Who's Next? A Thanagarian shape-shifter.