Wow, a winner already! Congratualtions to Metalexveemon of DA for guessing the character right:

Earnest Penfold of ‘Danger Mouse’

Now I suppose some of you are wondering why you didn’t win when you gave the ‘Earnest Penfold’ answer. Read the rule again:
YOU MUST GIVE THE CHARACTER’S FULL NAME AND WHAT MOVIE OR SHOW OR COMIC THE CHARACTER IS FROM
Most of you just gave the name and not the show. So to be fair, I stuck to the rule. Read the rules carefully next time.

Now to explain the clues:
-This character is not a human
Penfold is an anthro hamster

-This character is both short and small
Penfold is the shortest character in the show and is still illustrated as a real sized rodent. So he’s about 2-3 inches tall

-This character’s hobbies are dancing, martial arts, writing, and playing the saxophone. None of which the character is good at
In various episodes it shows Penfold doing these hobbies, much to Danger Mouse’s annoyance

-The character’s chief has only one eye
This is referring to Danger Mouse himself, he wears an eye-patch. Penfold refers to him as ‘Chief’

-Jigsaw
‘Jigsaw’ is Penfold’s nickname. He got that name because when he’s given a problem, he goes to pieces

-This character’s enemy has a green back with a little fuzzy thing with a big red nose
This refers to Baron Greenback (his name is mentioned there). Also his fuzzy pet caterpillar Nero, he has a big red nose

-This character once had over a billion clones made of themselves
In the episode ‘Tiptoe Through the Penfolds’, Greenback accidently clones billions of Penfolds

-This character once aged 50 years in a second
In the episode ‘Tampering with Time Tickles’, Penfold was hit by an ‘Aging Bomb’ and turned into an old man. Danger Mouse was turned into a child

-This character hates being called by their first name
Penfold mentions that he hates being called ‘Earnest’

-This character has an overbearing aunt
Penfold’s aunt from Wales is always complaining about Penfold and Danger Mouse. She believes they are just playing a childish game and are not really secret agents

-This character wears the same clothes all the time
Penfold wears the same suit in every episode

-This character does have an ego, but is still earnest and faithful
Penfold believes he has many fans. His name is mentioned there too, ‘earnest’

-This character does not like riding elevators
He’s always complaining about riding the base elevator to their vehicle

-This character has 4-eyes
This is the old expression for a person who wears glasses. Penfold does wear glasses

-This character is a parody of another famous character in classic literature
He’s a parody of Dr. Watson of the Sherlock Holmes series

-Fiddle carrots crumbs eck
These are expressions Penfold often uses.

-This character’s boss is strong enough to throw a piano
It is mentioned that their head boss Colonel K won a ‘piano-throwing’ contest

-This character is underrated
Penfold is not too well-know. So I wanted viewers not to just think about popular characters

-A clue is also in the submitted picture above
The picture is similar to Penfold’s suit


Well that’s it for this contest. It was fun. I may do another one later in the year.

Again, congratulations to Metalexveemon!