Flagg first appeared in The Stand as a demonic figure who wreaks havoc after a plague kills most of the population. He has a variety of names, usually initialed "R.F." but with occasional exceptions, such as Walter o'Dim (originally envisioned by King as a separate character) in The Dark Tower series. Flagg is described as "an accomplished sorcerer and a devoted servant of the Outer Dark", with supernatural abilities involving necromancy, prophecy, and influence over animal and human behavior. His goals typically center on bringing down civilizations through destruction and conflict. Stephen King was heavily influenced by Charles Starkweather (the teenager responsible for the murder spree in the 1950s that inspired Natural Born Killers), and has implied that Randall Flagg was modeled after him. It's also revealed in The Stand that Flagg and Starkweather went to high school together.
It has been theorized (and seems likely) that Randall Flagg was "He Who Walks Behind the Rows" from Children of the Corn. The hint comes in a sobriquet that includes all of the letters, in order, of the name Walter: "he Who wALks behind ThE Rows".
She looked. Neatly pegged white letters under glass read: THE POWER AND GRACE OF HE WHO WALKS BEHIND THE ROWS. The date was 27 July 1976 - the Sunday before.
'He Who Walks Behind the Rows,' Burt said, turning off the ignition. 'One of the nine thousand names of God only used in Nebraska, I guess. Coming?'
- Children of the Corn
The graphic novel Clay sells at the beginning of the novel is entitled The Dark Wanderer, and the main antagonist, the Raggedy Man, wears a red hoodie from Harvard, a reference to the Crimson King.
“I don’t know,” Jordan said. He looked up at Clay. “Where’s the Raggedy Man?”
“Is that what you call him?” Clay looked down at his sketch, which he was still carrying—the torn flesh, the torn sleeve of the pullover, the baggy blue jeans. He supposed that Raggedy Man was not a bad name at all for the fellow in the Harvard hoodie.
“I call him trouble, is what I call him,” Jordan said in a thin voice. He looked out again at the newcomers—three hundred at least, maybe four hundred, recently arrived from God knew which surrounding towns—and then back at Clay. “Have you seen him?”
“Other than in a bad dream, no.”
- Part 3: Gaiten Academy / Chapter 29
Sarah lives on Flagg Street, which is where Johnny later gets picked up by the cab which changes his life forever.
In retrospect it was the emptiness that horrified her, it had been five months of Cheyne-Stokes respiration. Eight months if you counted this summer, when she took a small apartment on Flagg Street in Veazie and did nothing but apply for teaching jobs and read paperback novels.
- Part I / Chapter 1
A man with the initials RF was the leader of a student protest group that set off a campus bomb and killed people. Randall Flagg was known to go by other names, usually with the initials RF.
The group—Militant Students for Peace, they called them-selves—planted the bomb in a lecture hall on the Danbury UConn campus. On the day of the explosion, Coleman Chemicals was hold-ing job interviews there between ten A.M. and four P.M. The bomb was apparently supposed to go off at six in the morning, when the building was empty. It failed to do so. At eight o’clock, then again at nine, someone (presumably someone from the MSP) called Campus Security and reported the presence of a bomb in the first-floor lecture hall. There were cursory searches and no evacuation. “This was our eighty-third bomb-threat of the year,” an unidentified Campus Secu-rity officer was quoted as saying. No bomb was found, although the MSP later claimed vehemently that the exact location—the air-con-ditioning duct on the left side of the hall—had been given. There was evidence (persuasive evidence, to Willie Shearman if to no one else) that at quarter past noon, while the job interviews were in recess for lunch, a young woman made an effort—at considerable risk to her own life and limb—to retrieve the UXB herself. She spent perhaps ten minutes in the then-vacant lecture hall before being led away, protesting, by a young man with long black hair. The janitor who saw them later identified the man as Raymond Fiegler, head of the MSP. He identified the young woman as Carol Gerber.
- Blind Willie / 5:25 PM
Brady Hartsfield uses a smiley face as his trademark, just like Flagg.
The last thing appears to be an actual letter—a fairly thick one, by the feel—in a business-sized envelope. It is addressed to Det. K. William Hodges (Ret.) at 63 Harper Road. There is no return address. In the upper lefthand corner, where one usually goes, is his second smile-face of the day’s mail delivery. Only this one’s not the winking Walmart Rollback Smiley but rather the email emoticon of Smiley wearing dark glasses and showing his teeth.
- Part 1: Det.-Ret. / Chapter 2
Flagg makes an appearance in The Eyes of the Dragon as an evil wizard attempting to plunge the fictional medieval city of Delain into chaos.
And one man thought and planned and brooded on something else: how to make sure that Roland's younger son, Thomas, should be crowned King instead. This man was Flagg, the King's magician.
Flagg introduces himself with a typical RF alias, after Roland has known him as Walter O'Dim and Marten Broadclock at various points in his life.
“Call me Fannin,” the grinning apparition said.
“Richard Fannin. That’s not exactly right, maybe, but I reckon it’s close enough for government work.” He held out a hand whose palm was utterly devoid of lines. “What do you say, pard? Shake the hand that shook the world.”
- Book 2 / Part V / Chapter 40
Graffiti on the turnpike references lots of familiar enemies (the Walkin Dude is one of Randall Flagg's aliases).
Someone had spray-painted over both signs marking the ramp’s ascending curve. On the one reading ST. LOUIS 215, someone had slashed WATCH FOR THE WALKIN DUDE in black. On the one marked NEXT REST AREA 10 MI., ALL HAIL THE CRIMSON KING! had been written in fat red letters. That scarlet was still bright enough to scream even after an entire summer. Each had been decorated with a symbol.
- Part 1 / Chapter V: Turnpikin'
One of Randall's aliases is Walter O'Dim; here we learn he's gone by yet another related name.
He’d always gone dressed in such fashion, when he could; in certain provinces to the south even of Garlan he had been known as Walter Hodji, the latter word meaning both dim and hood. But this particular lid (borrowed from a certain deserted house in the town of French Landing, Wisconsin) had done him no good at all, had it?
- Part 2 / Chapter III / Section 5
A reference to one of Flagg's pseudonyms, Walter O'Dim?
"The wolfs seemed more afraid of him than of his father, although the son carried no whip. They said he was dim." "Dim," Jack mused. "Yes. It is their word for one who is hard to see, no matter how hard ye look for that one. Invisibility is impossible - so the Wolfs say - but one can make himself dim if only he knows the trick of it."
- Part Four / Chapter 34 / Section 8