Buster Bunny (Tiny Toon Adventures)
The Buster Bunny we know is a slick, quick-witted blue rabbit in a red shirt, a cool-kid update on his mentor, Bugs. Adler's voice for Buster is packed with confidence and a fast-talking charm that perfectly matches his energetic design. But early concept
art tells a different story. In some initial designs from 1989, Buster was named "Bitsy Bunny" and sported a blue shirt instead of his signature red one. While a simple color swap might seem minor, the change to red makes the character pop, visually separating him from the cooler tones of the show’s world and giving him a heroic, leading-man energy. The name change from the softer-sounding "Bitsy" to the more assertive "Buster" also better reflects the punchy, in-your-face comedic persona Adler would perfect. The final design feels intrinsically linked to that vocal performance—it's hard to imagine Adler's boisterous voice coming from a rabbit named Bitsy.
Cow and Chicken (Cow and Chicken)
Voicing both titular characters, Charlie Adler had the monumental task of creating a sibling dynamic out of thin air. He gave Chicken a perpetually annoyed squawk and Cow a sweet, simple-minded tone that could escalate into a bellowing cry for her brother. The designs are bizarrely perfect—a scrawny chicken and a giant cow who are somehow biological siblings with human parents. Creator David Feiss famously conceived the idea as a bedtime story for his daughter, which explains the surreal, dream-like logic. Early development art shows that while the core concept was there from the start, Feiss experimented with their shapes and expressions. Some early sketches show a slightly more conventional, less exaggerated art style before he leaned into the wonderfully grotesque look that defined the show. The true evolution, however, came from the Red Guy, a devilish character also voiced by Adler. Feiss revealed the character came to him in a dream, and he was incorporated into the pilot after the initial story felt like it was missing something. This addition cemented the show's signature brand of chaotic, often-unsettling humor.
Ickis (Aaahh!!! Real Monsters)
As the neurotic, insecure, and perpetually terrified monster-in-training, Ickis is a bundle of delightful contradictions. Adler's performance captures this perfectly, vacillating between a panicked yelp and a roar of misplaced confidence. His design is iconic: a small, purple, rabbit-like creature who can loom large to scare humans. But the journey to this final look wasn't straightforward. The show, created by Gábor Csupó and Peter Gaffney, had a distinctively rugged and unusual art style. In the development phase, the proportions and features of the main trio—Ickis, Oblina, and Krumm—were experimented with extensively. Early concepts played with making Ickis more traditionally frightening before landing on the final, more vulnerable design. This choice was key; making Ickis smaller and giving him big, expressive eyes made him more relatable and turned his deep-seated anxiety into a comedic engine. Adler's high-strung vocal performance works precisely because Ickis looks like he’s in over his head, a visual-vocal harmony that wouldn't have been as effective with a more conventionally scary monster.
I.R. Baboon (I Am Weasel)
A frequent collaborator with David Feiss, Adler also voiced I.R. Baboon, the jealous and grammatically challenged foil to the suave I.M. Weasel. Adler's voice for I.R. is a masterpiece of buffoonery—a whiny, indignant screech that perfectly captures the character's incompetence and frustration. But I.R. Baboon almost didn't exist at all. When Cartoon Network picked up Cow and Chicken for a full series, they requested a middle seven-minute cartoon to fill the half-hour slot. Feiss initially had other ideas for the backup segment, including one called "Uncle Mustard," before settling on I Am Weasel. The very creation of I.R. Baboon was a product of network development needs. Had Feiss gone with one of his alternate ideas, one of Adler's most memorable and hilariously pathetic characters would never have graced the screen, leaving a significant void in the pantheon of 90s cartoon sidekicks.
