The Mystery Cartoon Character Game, ongoing-ier.

Can't say I ever saw this one.

I think this might be Emotion, from the Disney short Reason and Emotion (1943).

That is correct! The cartoon starts with a baby who only has Emotion. When the baby is a little older, Reason appears.
They are "roommates" in the child's head and you see how Emotion lives in the moment while Reason is level headed.

Take it away!!

Thanks!

Oh dear.. now I've got to find another character...
Ah! Here's one we haven't had yet!

1) I'm a green-faced cigar-smoking clown and I share my name with another green character (as is seen in his first appearance).
2) I am the first character animated by my creator - watch me move!
3) I appear in an animated feature 78 years later.

Though I thought this one would be a toughie, I found him rather quickly. It's Flip The Clown, from "Little Nemo In Slumberland."

Spot on, Emeraldisle - it is Flip.

1) Flip is also, of course, the name of Ub Iwerks' frog, seen to be green-bodied in his first film, the 2-color Technicolor Fiddlesticks.
2) Winsor McCay animated characters from his Little Nemo in Slumberland strip in 1911. The animation begins with a held drawing of Flip, with the caption "WATCH ME MOVE" above his head.
3) The 1989 Japanese/American animated feature film Little Nemo: Adventures in Slumberland.

Well done - you're up again!

Thanks, Pete. Now here's another I didn't plan on posting, but will anyway:

1. I appear in a handful of episodes near the end of the series' run, as a younger version of the title hero.

2. Although I'm more or less an orphan, I refuse to give up looking for my father.

3. The first villain I go after shares his name with a classic Heart song.

I thought one as easy as this wouldn't need more clues, but here I go:

4. I use artificial wings for flight.

5. When I'm rescued, I'm able to remember everything except my own name.

6. My name is changed when the title character becomes an attorney.

I've been doing research and I'm going to guess that it's Birdboy from Birdman and the Galaxy Trio.

Yes, Saltyboot, it's Birdboy all right. Now to explain:

1. He was seen in a handful of episodes as the series wound down, and had a costume that resembled Birdman's.

2. His father was never seen again after their boat was destroyed, but Birdboy was convinced he was still alive.

3. The first villain he pursued along with Birdman and Avenger was The Barracuda.

4. Unlike Birdman, who had natural wings, Birdboy had mechanical ones.

5. When Birdman saved him, he had paramnesia. That is, he remembered what happened when he and his dad arrived on the island, but couldn't remember his own name.

6. For "Harvey Birdman: Attorney At Law," his name was changed to Peanut. Go figure.

So you have the ball in your court, Saltyboot. Good job.

Great! Now here's one that I finally put together.

I appeared in two shorts.
The relationship with my best friend is rather ironic.
I prove to be quite the handful.

I have absolutely no idea. This will take research.

Is this Chester perhaps? From "Tree for Two" and Dr. Jekyll's Hyde?"

I know I don't know. I don't even know where to begin to look!

Nope, not Chester. Hopefully these next clues will do it.

In my first short, I grow to adulthood.
In my second short, I stay in puppyhood.
When you imagine my owner, it probably wouldn't be this guy.

I still haven't the slightest clue. Maybe someone else has seen it.

All righty then. Here are the last three clues, and hopefully these will point everyone in the right direction.

My shorts are not from Warner Bros.
My owner is very goofy.
My shorts were made one year apart.

I'm afraid you got me on this one. Perhaps another player knows.

Well that goofy clue gave me a big hint. Apparently Goofy had a dog called Bowser at one point--who knew?
Also, is that considered slavery?

Yes it is Bowser, Goofy's dog. Ironic, isn't it?
Bowser was in two shorts, Man's Best Friend (1952), and Father's Weekend (1953).
In the first short, he grew up. In the second one, he stayed a puppy.

You're up Glowworm!