Roaring Kitty, a trader and YouTuber with a cult-like following has returned, causing GameStop's stock to jump 50% on Monday.

Roaring Kitty, real name Keith Patrick Gill, gained prominence in January 2021 when he set off a surge in GameStop's stock, Reuters reported. At one point, on January 28, 2021, shares reached over $500 in pre-market trading before dropping to $483 during trading hours, according to The Street.

Gill, 37, is now back after taking a years-long hiatus. He seemingly confirmed his return Sunday on X by posting a photo of a man intensely playing a video game.

Gill continued to garner support and adulation from fans on Monday as he posted clips from movies on his X account, including footage of Thanos grabbing the Infinity Gauntlet from Marvel Studios' "Avengers: Infinity War."

Gill's comeback has already caused commotion, but here's more information on who Roaring Kitty is.

Who is Roaring Kitty?

Keith Gill became popular after creating Roaring Kitty on YouTube and "DeepF***ingValue" on Reddit, according to Reuters.

Gill is from Brockton, Massachusetts, and a former track and field star at his high school, according to Investopedia and The Wall Street Journal. Before becoming Roaring Kitty, he worked at a subsidiary of MassMutual as the director of education and wellness, the WSJ said.

Gill joined X, formerly known as Twitter, in 2014 under the name @TheRoaringKitty, Investopedia said.

The 2023 film "Dumb Money" chronicles Gill's time as Roaring Kitty and shows how his efforts affected Wall Street. Actor Paul Dano plays Gill in the film.

How did Keith Gill influence people to buy GameStop?

Gill's never-give-up personality, which the movie "Dumb Money" depicts, helped him influence people to buy and hold GameStop during the short squeeze in January 2021.

A short squeeze occurs when "the price of a stock moves sharply higher, prompting traders who bet its price would fall to buy it to avoid greater losses," by closing out their bets, according to Investopedia. That rush to buy, however, results in more demand and a higher price for the stock. Speculators and traders who have short positions in a stock will face heavy losses, while people who bet the stock would rise will benefit.

What happened to Keith Gill after the GameStop surge?

On January 28, 2021, the same day GameStop's shares reached over $500, stock trading company Robinhood froze trades for GameStop, according to CNET.

Robinhood's decision led to the company receiving backlash from small investors, and Gill being ordered to testify before the U.S. Congress alongside U.S. hedge fund managers, Reuters reported.

GameStop's stock continued to decline month after month, leaving those who invested either thankful they cashed out early or angry they held and ended up with nothing.

It is unclear how much Gill made off of GameStop during the short squeeze, but Business Insider reported that his stock holdings in the game company were valued at $48 million at the height of the surge. He initially invested $53,000 into GameStop in 2019, according to the outlet.