Luigi Mangione Cheered Online with Flood of Super Mario, 'Sopranos' Memes

Luigi Mangione is now charged with the cold-blooded killing of the UnitedHealthcare CEO ... and social media is being flooded with memes hailing the suspect as a hero.

Here's the deal ... 26-year-old Mangione was apprehended Monday and hours later the Manhattan D.A. charged him with murder for the brazen December 4 fatal shooting of Brian Thompson. He's also facing charges of criminal possession of a weapon, possession of a forged instrument, and 2 counts of possession of a loaded firearm.

Mere minutes after the suspect was identified and internet sleuths found his socials ... admirers began posting Super Mario Bros. and "Sopranos" memes celebrating Mangione.

Even before Mangione had been identified ... morbid devotees held a look-alike contest in NYC, while others were buying the jacket they thought was the same as the one worn by the suspect.

At one point on Macy's website over the weekend ... more than 6,000 people were viewing the jacket at the same time -- and nearly 700 had been sold in the past 48 hours, according to an item-popularity tool on the site.

Monday morning ... Mangione was busted in Altoona, Pennsylvania as he sat inside a McDonald's restaurant. A customer recognized Mangione from widely circulated wanted posters following Thompson's murder, and told an employee ... who then contacted local police, who responded and cuffed the suspect.

Authorities recovered the alleged pistol Mangione used in the murder and a 3-page manifesto he'd written railing against corporate America and the healthcare industry, according to police.