(CNN) Beloved internet meme Pepe the Frog has gone through various incarnations over the years, most of them innocuous and amusing.

But recent appropriations of the smirking green frog as Adolf Hitler, a Klansman and numerous racist caricatures have earned him a spot in the Anti-Defamation League's database of hate symbols

"Once again, racists and haters have taken a popular Internet meme and twisted it for their own purposes of spreading bigotry and harassing users," Jonathan A. Greenblatt, ADL CEO said in a statement . "These anti-Semites have no shame. They are abusing the image of a cartoon character, one that might at first seem appealing, to harass and spread hatred on social media."

The designation does not apply to all Pepe memes because most of them are not "bigoted" in nature, the ADL said. You'll likely know one when you see one.

Feels good, man

It wasn't always this way for Pepe, who first appeared on the internet in 2005 in artist Matt Furie's "Boy's Club" cartoons.

In 2008, a comic of Pepe with his pants at his ankles while urinating, captioned "feels good, man," spread through online community 4chan, according to KnowYourMeme

Original made in USA mass produced common Pepe for when you share your birthday with the G... https://t.co/7K6Arq1x9M pic.twitter.com/MNrg1uNntG — 🐸King Robbo 🐸 (@realkingrobbo) June 14, 2016

His bemused smirk was made for the internet, and a meme was born.

Pepe was manipulated over time to capture the range of the human experience, including Sad Frog, who was often paired with the phrases" Not Good Man," "Feels Bad Man," or "You Will Never..." to Smug Frog, Angry Pepe, Keith Haring Pepe, even supposedly Rare Pepes

#TheKekOffensive

WARNING: THIS RARE PEPE IS PROTECTED MY ANTI-PIRACY LAW, DOWNLOAD OR RETWEET IS ILLEGAL

DO NOT SHARE pic.twitter.com/i05dzHiLBM — Luis Eduardo (@Luisedgm) September 20, 2016

A decade later he had solidified his place among "normies" in mainstream internet circles, becoming one of the biggest memes on Tumblr in 2015.

The good times couldn't last.

Feels bad, man

As the meme proliferated in venues such as 4chan, 8chan and Reddit, criticized as a breeding grounds for all manner of inflammatory imagery, a subset of Pepe memes came into being that centered on racist, anti-Semitic or other bigoted themes, the ADL said.

These nazi frogs are everywhere.

Someone Just pissed me off. Went to their site.&&& U LEARN ALOT FROM PPLS SITES‼️ pic.twitter.com/3cC1ROlmNE — Cher (@cher) September 17, 2016

The 2016 US presidential campaign exacerbated the phenomena as white power movements came out to endorse Donald Trump, drawing in Republican nominee Donald Trump.

After Hillary Clinton said most of Trump's supporters were in a "basket of deplorables," Donald Trump Jr. shared an altered version of the movie poster of "The Expendables" on Instagram. It showed Pepe among Trump Senior and other conservative figures labeled "The Deplorables."

The Clinton campaign fired back with a post, " Donald Trump, Pepe the frog, and white supremacists: an explainer " on why "that cartoon frog is more sinister than you might realize."

The internet responded with ridicule.

A photo posted by Donald Trump Jr. (@donaldjtrumpjr) on Sep 10, 2016 at 7:18pm PDT

Not all Pepes are 'bigoted'

Context matters, though. Not all Pepes are sinister, the ADL said.

"The mere fact of posting a Pepe meme does not mean that someone is racist or white supremacist," the group said.

"However, if the meme itself is racist or anti-Semitic in nature, or if it appears in a context containing bigoted or offensive language or symbols, then it may have been used for hateful purposes."