“Omar comin’.”

Nearly every character in the Baltimore imagined by HBO’s “The Wire” knew what those words meant — and shuddered, or ran, when they heard them. Omar Little, the infamous stickup artist, would soon be arriving, long duster flapping, beloved sawed-off shotgun in tow. Hide the stash. Hide the cash. Baltimore’s Robin Hood is here to rob the dealers.

Omar was portrayed by the prolific Michael K. Williams, who was found dead in his apartment on Monday. As tributes to the 54-year-old actor poured out on Twitter, one thing was clear: It wasn’t only the characters in “The Wire” who knew Omar simply by his first name. Nearly everyone in the real world did, too.

“I’ll never forget Omar,” tweeted author William Gibson. “Omar might be the best character of all time,” tweeted Rep. Jamaal Bowman (D-N.Y.).

“Omar Little is a Top 10 all-time TV character — menacing one moment, cleverly hilarious the next and, at the same time, he’s a completely unique form of queer, Black masculinity, driven as much by desire as capitalism,” tweeted Hollywood Reporter TV critic Daniel Fienberg. “David Simon created Omar, but Michael K. Williams MADE him.”

Few television characters truly become embedded in the cultural consciousness — particularly in the modern era of a niche show for every niche interest. Fewer still can be summed up with a single name. Tony Soprano, Walter White and Don Draper couldn’t pull that off.

Omar did.

And Michael K. Williams is the reason.

(Spoilers ahead, for those of you with “The Wire” still on your to-do list.)

Co-creators David Simon and Ed Burns based the character on several stickup men they encountered on the streets of Baltimore when working as a reporter and homicide detective, respectively. Most notable among them was Donnie Andrews, who robbed drug dealers in Charm City before turning away from crime and dedicating his life to helping prevent young people from following in his footsteps. Andrews, who died in 2012, worked as a consultant on “The Wire.”

Like the real-life Andrews, Omar lived by a set of strict — if self-styled — moral values. He’s a stone-cold killer who never curses. In one episode, he robs a corner store owner of a drug stash, then pays him for a pack of cigarettes. As Omar says, “A man got to have a code.”

Simon further tweaked the character slightly by making him openly gay. “I thought Omar, as an unaffiliated character, could be boldly and openly homosexual in a way that a gay man within the organized drug trade or within the police department could not be,” he told the Guardian in 2008.

That decision, Williams said, also helped normalize being gay in some communities.

“In the hood, especially among the Black community, homosexuality is taboo,” Williams told the paper. “But I get real gangsters coming up and saying, ‘Omar’s my man! I love Omar!’ I think it might have made some people think differently about things.”

Michael K. Williams, an Emmy-nominated actor, was found dead on Sept. 6 in his Brooklyn home. He was best known for his role as Omar Little in HBO's "The Wire." (Julie Yoon/The Washington Post)

Originally, Omar was slated to die seven episodes into the show’s five-season run. But thanks to the “passion” in his performance, Williams said, Simon and Burns expanded his story — and his arc became one of the most affecting and beloved of the entire series.

In 2006 — the middle of “The Wire’s” run — USA Today named Omar as one of the “10 reasons we still love TV,” writing, “No one who saw Williams’ performance on The Wire could fail to appreciate it.” In 2012, President Barack Obama called Omar his favorite character on the show, saying, “That guy is unbelievable, right?”

Omar may have gotten many of the show’s best lines, but Williams transformed them into classics on par with “Leave the gun, take the cannoli.”

You come at the king, you best not miss.

All in the game, yo, all in the game.

A man got to have a code.

Boy, you got me confused with a man who repeats himself.

The game is out there, and it’s either play or get played.

Money ain’t got no owners, only spenders.

Not that he even needed to speak. Williams could take something as simple as whistling “The Farmer in the Dell” — an Omar favorite when he’s on the way to wreak havoc — and forever alter the viewer’s association with the tune.

Portraying a murderous stickup man wasn’t necessarily the most natural fit for Williams. On the first day of filming the show, he was confused by Omar’s iconic shotgun. “He didn’t know which end was which,” Simon told the New York Times. “Mike is a beautiful man, but a gangster he is not.”

Determined to nail his character, Williams asked a drug dealer to show him the ropes.

“I’d spent a long time on the streets of Baltimore going deep into that world,” he said in 2008. “I would be out after 2 a.m., seeing fights, hearing shots fired. I needed to learn the details of how they walked, how they spoke. Baltimore is different to Brooklyn.”

The role, though, wasn’t easy on Williams. While portraying Omar, he fell into addiction and “lived a double life as a doper in Newark’s most dangerous neighborhoods — doing drugs ‘in scary places with scary people,’ ” he told NJ.com in 2012. As Williams recalled, he began feeling like Omar, like a character — as he struggled with drug addiction. “I suffered from a huge identity crisis. … In the end, I was more comfortable with Omar’s skin than my own. That was a problem.”

“People didn’t even call me Mike, they called me Omar. But that wasn’t unusual because everybody had an alias,” he added. “No one was called their government (name) on the block, so they called me Omar or ‘O.’ That mixed with my identity crisis and my addiction — and it was not a good mix. I had to stop trying to be Omar and just be Mike.”

Williams often spoke about how he gave part of himself to the character, perhaps lost part of himself to Omar. When the character was finally killed, Williams told MTV, “I feel like I lost one of my best friends.”