Junior is a small teal colored, translucent amoeba with a lighter colored membrane and a bunch of aqua contractile vacuoles floating around inside of his cytoplasm. He has no physical features, aside from a simple face, comprised only of eyes, that are partially obscured by his hat, and a mouth with a missing tooth. He wears a black Kangol hat. In the pilot episodes, "Whoopass Stew" and "Crime 101", Junior's contractile vacuoles were purple instead of aqua. It wasn't until his official series debut in "Geshundfight", he was finally given his current appearance.
Junior is the least original member of the bunch, as most of the things he says are repetitions of things that Slim says, preceded by "Yeah". He is an idiot like the other two, but more of a mid-level man, as he is not as smart as Bossman, but not as stupid as Slim. He is also the quietest of the bunch, and rarely brings anything to the table, that isn't just a rehash of what Slim says. His lack of participation and group involvement is good for keeping him out of the line of fire, between Bossman and Slim, when things get heated between the two, and they get into an argument, that eventually spirals into a physical fight. He can often break up their fight, by using his moderate intelligence, to bring up a valid point, or point out something important, which gets the two to either come to an agreement or stop fighting to focus on something more important.
- Whoopass Stew
- Crime 101
- Birthday Bash
- You Snooze, You Lose
- Daylight Savings (Non-Speaking Cameo)
- Bought and Scold (Non-Speaking Cameo)
- Film Flam (Non-Speaking Cameo)
- Shotgun Wedding (Pictured)
- Divide and Conquer
- See Me, Feel Me, Gnomey
- Live and Let Dynamo (Non-Speaking Cameo)
- A Made Up Story (Non-Speaking Cameo)
- The Powerpuff Girls Rule!!!
- His voice and verbal tics are based on notorious gangster, Al Capone.
- He is the only member of The Amoeba Boys, who doesn't wear a fedora.
- He is one of the characters who wears a Kangol hat, other is Snake.
- In the pilot episodes, Junior used to be named "Tiny".
- Despite this name change, the Cartoon Network website still erroneously lists him as "Tiny".
- In "Powerpuff Girls Z", his anime counterpart is a pink female amoeba named "Violet", who wears a sunhat with a flower in it.