BALTIMORE (AP) – Omar never saw it coming. Neither did the actor who plays him, Michael K. Williams.

Stickup man Omar Little, perhaps the most beloved character on the HBO series "The Wire'', was dispatched in shocking fashion on Sunday night, taking a bullet to the back of the head as he bought a pack of Newports at a convenience store. His killer: Kenard, a boy no older than 12 and a minor player in the drug gang Omar was battling.

It was a bitterly ironic end, in keeping with "The Wire's" resistance to conventional, crowd-pleasing story arcs.

"I was rooting for him like anybody else. I'm not going to lie," Williams said from Phoenix, where he's shooting a movie. But he had no illusions about the odds Omar would confront when he returned to Baltimore to avenge the death of a friend.

"I kind of knew that if he went back to Baltimore by himself, there was a highly probable chance he wasn't going to make it out of that city."

Williams found out that Omar would "catch one" the same way other actors were told of their characters' deaths: He read it in the script. No one gets special treatment on "The Wire'', he said, noting the actors who played Stringer Bell and D'Angelo Barksdale also got little notice before their characters were killed off.

"When Larry Gilliard (who played Barksdale) got his information, he was in the hair and makeup trailer. Idris Elba (Bell) got his a few days before he had to be on set for his death scene," Williams said. "It keeps it really fresh and organic, keeps everybody on their toes, doing their best job, not getting too comfortable."

Omar had been in danger for a while. Targetted by Marlo's killers, he miraculously escaped a trap by leaping from a sixth-storey balcony. Then he vengefully limped around the streets on a makeshift crutch as he harassed Marlo's minions.

Viewers who paid close attention to Kenard were rewarded: As other fled in terror from Omar, the boy made a point of how unimpressed he was with the injured gunslinger.

Williams brought a foreboding sadness to his performance in this, the show's fifth and final season. Omar lacked his usual swagger; he became reckless, desperate, alone.

"You kind of see that he feels like the last of a dying breed," Williams said. "All the blood that's on his hands, it all comes to a head. At least that's where I was mentally when I was doing those scenes."

Inspired by real stickup men series creator David Simon met during his time as a crime reporter for The Sun, Omar was also larger than life, with his intelligence, moral code and florid, profanity-free speaking style ("indeed"). Plus, he was gay, a fascinating wrinkle.

While robbing drug dealers was lucrative for Omar, he often did good deeds and was hailed by critics and fans as a modern-day Robin Hood. As he told drug kingpin Marlo Stanfield while robbing him at a poker game, "Money ain't got no owners. Only spenders."

Even presidential contender Barack Obama expressed his admiration for Omar – albeit with the caveat that he didn't endorse Omar's behaviour.

While the episode aired on Sunday night, it was available on demand six days earlier, and news of Omar's death provoked outrage and sadness on blogs and message boards devoted to the show. Some even touted conspiracy theories, arguing that it wasn't Omar but his long-lost brother who died.

"His murder was swift and unexpected, probably not unlike the way many guys in his line of work meet their ends," fan Anthony Wilson wrote on his blog. But the stark realism of Omar's death stood in contrast to the optimism he represented.

"He beat the odds time and again over five seasons," Wilson wrote. "I thought Omar was supposed to prosper. Why get him got now? Doesn't make sense to me."

Williams, though, is prospering. Omar was the first recurring TV role for the 42-year-old actor, who acquired his distinctive facial scar when he was slashed with a razor during a bar fight. The wrap party for the show's fourth season was modeled after a high school prom and graduation, and it was an emotional night for Williams, a high school dropout who grew up in rough East Flatbush, Brooklyn.

"I felt like I was graduating from college," Williams said.

"I felt something inside that told me I was ready to go pro now."

And he has, wrapping roles in Spike Lee's Second World War epic "Miracle at St. Anna'', the blockbuster sequel "Hulk 2" and "Wonderful World'', an independent film starring Matthew Broderick.

After he finishes his current project, "Addicts'', he'll move on to "The Road'', based on the Pulitzer Prize-winning novel by Cormac McCarthy ("No Country for Old Men"). He doesn't even have a place of his own, living in hotels and temporary housing as he hops from set to set, his belongings in storage.

Perhaps nothing he does, though, will touch audiences the way Omar has.

"I crossed some line with this character into people's minds and hearts that I don't think is the norm," he said. "People are very passionate about Omar, and it's a very humbling feeling, the love that gets thrown at me for portraying him. I've heard words like, 'Thank you for your courage'."