Who is Conor McGregor?

No mixed martial artist has ever ignited passion or demanded attention like "The Notorious" Conor McGregor.

He brashly predicted in 2014 that he'd climb to greater heights than anyone before him in the industry, forecasting multiple titles and pay-per-view records. While eyes rolled throughout the MMA community, McGregor seemed fixed on a film strip only he could see.

The proclamations were viewed as the ramblings of a madman, then, later, those reflecting unparalleled self-belief and, eventually, outright premonition. All three might have been true the entire time.

It's widely reported but impossible to overstate: In barely four years' time, McGregor went from collecting welfare checks to depositing the biggest check in the history of his sport.

He entered the fight game, he says, not for prize or sport, but to defend himself in the inevitable schoolyard scraps in Dublin's Crumlin suburb. Win or lose, specifics of every dustup stuck with McGregor. He'd obsess over how he could have moved or evaded differently to be more efficient the next time around -- a schoolboy doing his homework.

As his family relocated west to Lucan, Ireland, in his late teens, McGregor expanded his training beyond boxing while working blue-collar jobs -- industrial plumbing, among them -- to buoy the dream of professional fighting. Five years, 12 wins and two Cage Warriors titles later, Ireland's fighting son signed with the UFC.

The nation is known for supporting its own like few others, but Conor made it easy. He won each of his first seven UFC fights, finishing six by knockout -- the only exception: a unanimous decision over now-featherweight-champion Max Holloway in which McGregor tore his ACL. The Irish tricolor packed arenas in Boston, Dublin and Las Vegas, with echoed chants more resembling European football than cage fighting. McGregor fed on the energy and feasted on the opposition, both before and during bouts.

Psychological warfare, a tool parlayed into his unparalleled popularity, became as synonymous with McGregor as his granite left hand.

As he ran through Holloway, jiu-jitsu black belt Diego Brandão and well-rounded veteran Dustin Poirier, McGregor used pre-fight interviews and media events to land verbal jabs and crosses. As stakes raised in title bouts against All-American wrestler Chad Mendes, pound-for-pound king Jose Aldo and lightweight champ Eddie Alvarez, McGregor's intellectual attacks intensified.

Promotional media conferences became untimed rounds, which McGregor won ruthlessly and unanimously. Contemporaries, especially those in his division, showed clear contempt for the tactics. But as pay-per-view and gate records came crumbling down, so, too, did those standing across the Octagon.

Normally unflappable veterans Aldo and Alvarez, in particular, succumbed to emotion in the cage and fell victim to early knockouts. For Aldo, a nine-year reign came crashing down, face-first, in 13 seconds, a record for UFC title fights.

McGregor predicted Aldo's investment would lead to reckless overextension, which he could counter to render the champ unconscious. McGregor said in a separate interview he noticed Aldo's right hand twitching during stare-downs, a subtle tell. At UFC 194, Aldo's looping right was dodged and answered with a pinpoint left cross, putting the Brazilian to sleep and passing the mantle, a called shot of Ruthian proportions.

"Mystic Mac" -- a self-given nickname months prior -- had already made a habit of turning sequential visualization into reality in wins over Brandão, Poirier and Mendes.

Speaking with Irish photojournalist Dean Kelly in December 2008, a pitchy, pimply McGregor said, "My dream is to be world lightweight champion in the UFC, have more money than I know what to do with and have a great life for my kids." A recent photo with his month-old son, Conor Jack, in a baby Lamborghini suggests that has come to pass, too.

In postfight interviews, McGregor shows a mix of gratitude, respect and confidence, but never surprise. He is a self-fulfilled prophecy, and The Notorious One has taken the MMA world by storm.

"Maybe they want to see you win. Maybe they want to see you covered in blood," he said. "As long as they're paying, that's all that matters."

Promoters, fans -- they're all paying, unlike ever before.