The character of Mr. Crocker, who desperately tries to uncover Timmy’s fairies in the series, was inspired by Walter Kornbluth, Eugene Levy’s character from the 1984 feature film Splash, who tried to prove the existence of mermaids.
According to Fairly Odd Christmas, Crocker doesn't really need glasses; he uses them to look smart/like a geek. Also, it was revealed that Crocker dyes his hair and he's actually a redhead.
In the video game, Nicktoons Unite during the battle with Crocker, he was wearing a gold armor but in the final battle with the other villains, Crocker was in his teacher clothes.
His voice sounds similar to Mr. Burns, a character from the animated series, The Simpsons, which Butch Hartman is a fan of that show. Also, both characters have a hump on their backs and sometimes Crocker says "Excellent!" like Mr. Burns. However, Crocker's voice actor Carlos Alazraqui said that he based Crocker's voice on the comedians Richard Dreyfuss and Gene Wilder, so it's likely the Mr. Burns similarity was purely a coincidence.
Butch Hartman originally created Crocker for another show of his that did not get made. After plans for said other show were canned, Crocker was integrated into the Fairly OddParents cast. Also, according to Butch Hartman's list of favorite episodes on iTunes, Crocker was originally intended to be a one-shot character.
It was revealed in Crocker Shocker that his overwhelming belief in fairies was the sole source of power for all of Fairy World. Since the end of Crocker Shocker, people similar to him are also used as the sources of power for Fairy World.
In "Pipe Down", Crocker spots Timmy, Cosmo, and Wanda and does his usual fairy godparents spasm frantically, but since there is no sound, no one, for once, can hear him scream!
Denzel Crocker made more appearances since Season 7 onward, replacing Vicky as Timmy's most frequent antagonist in the series. His appearances exploded in Season 9, appearing in the majority of episodes since then. Though many of these appearances were minor, and their usual purposes were punch line jokes.
Denzel Crocker can be considered to be a foil to Vicky, as he is often portrayed as being a sympathetic and/or comedic villain while Vicky is typically portrayed as being a frightening and unsympathetic villain.
Also, both of them became "flanderized" in the newer seasons. While Vicky became an even more destructive and evil villain than she was before, Crocker became more comical and bumbling (even though he was often portrayed as a comical villain from the beginning, he was still a serious threat), but in the newer seasons, Crocker isn't as evil as he was in the first 6 seasons. This is supported by the fact that Timmy and Crocker often teamed up in the newer seasons. They have been teamed up temporarily in the older seasons as well but the two were still considered to be arch-enemies. In the recent seasons, despite the fact that Crocker can still be evil, he has been acting more friendly towards Timmy.
He can also be considered as a supporting character or an "on and off" antagonist (instead of a true villain) in the newer seasons because of the aforementioned reasons.
He is one of the few, if not the only character with a theme song that plays in the title screen of any episode he is the antagonist (or, similar arranges). Curiously, it's the same arrange in Abra-Catastrophe!'s opening, a movie where he is the main antagonist.
He's been hunting fairies since 1975.
He's at his worst on March 15th.
Mr. Crocker is very similar to Mr. Lancer from Danny Phantom. They're both weird teachers whose dialog features frequent sarcastic humor, they're both treated with disrespect, they're both underpaid and under-appreciated, and they're both creations belonging to Butch Hartman. However, while Mr. Lancer wishes for his students to succeed, Mr. Crocker enjoys failing them.
He was a very kind person when he was a kid before his fairies were taken away. He also had saved Mr. Turner from being hit by a truck as a kid resulting in saving Mr. Turner's life.
In the episode 'Timmy's Secret Wish', Denzel Crocker is aged by 50 years more, making him 103 years old. However, his appearance has not changed a single bit. This is because his trauma aged him all at once.
Saying "Fairy GodParents!" "Fairies!" "Fairy!"
Giving Timmy "F's".
Saying "This may be the work of..." (In Birthday Wish!, he said the same thing to Tootie, but in one scene he said "Is this cake may be the work of...give me a second...[Inhales] Fairy GodParents?!" when Tootie has Timmy's fairies because of his guiltiness of Timmy not seeing 3 invitations and just looked at the coupon)
In the newer seasons, a common running gag associated with him is that he thinks ordinary people/stuff are magical and not recognizing the actual magic around hím. This is due to his intelligence being really decreased.
It's noted in "Formula for Disaster", that Crocker once was in Ninja school, was taught to be a ballerina, wanted to be a cat burglar (but didn't know what to do with a bunch of cats, a pun on the term for a jewel thief), and could never (ever, EVER) go back to Cincinnati. As a matter of fact, a sign at the end of the implied episode has "CROCKER FREE SINCE '83" at the bottom, with two Anti-Crocker stickers at the bottom, below the saying. It seems he was banned from Cincinnati in 1983.
In Remy Rides Again, Crocker states that Stephen Hawking was his college roommate, which indicates that Crocker must have been born around 1942, because Hawking was born that year. This is impossible since he was seen as clearly being 10 years old in 1972. This means that Hawking was born in 1962 instead of 1942 in the Fairly OddParents universe since there is often anachronisms in the show relating to people's ages (Adam West is shown younger in this universe even though he should be around 80 at this point).
Despite Crocker being born in 1949, he is 10 years old in 1972, when he should really be 23 years old.