Stephen King works related to The Dark Tower series
Apart from the seven books in Stephen King's The Dark Tower series, many of his other works are connected to this series to varying degrees .
Major connections
'Salem's Lot
Father Callahan, a major character in the latter part of the series, first appears in this novel, originally published in 1975, seven years before the first book in the series, and twenty-eight years before his re-appearance in the fifth.
The Stand
The world of this novel, first published in 1978, is visited in the fourth book of the series. Also, Randall Flagg is one of the main characters.
The Talisman
Twinners
Skeleton Crew
In the novella, The MiST, the cause of the Mist is alluded to be a tear between universes, similar to the Todash Darkness, a concept explored in the series, both of which supposedly renders it's inhabitants "blind" and contains horrible creatures which prey on them. Additionally, several creatures described are physically similar to some of those shown in the series.
It
In this novel, it is stated that the enemy of It is a turtle. The Turtle is the guardian of the portal opposite the Bear (Shardik) in the The Dark Tower III: The Waste Lands. It is also stated in chapter 9, section 11, (page 430 in the 1986 hardback release)"In this universe there might be roses which sing."
The Eyes of the Dragon
Randall Flagg is a villain in this novel, and in the second book of The Dark Tower series, The Drawing of the Three, Roland alludes to a time when he encountered Thomas and Dennis chasing after Flagg.
Insomnia
The novel's main character, Ralph Roberts, is made to save the life of the infant Patrick Danville, a major character in the last book of the series. Additionally, various allusions are made to the Dark Tower, and Roberts even meets the Crimson King in person.
Rose Madder
Desperation
The Regulators
Bag of Bones
Hearts in Atlantis
The book, "Hearts in Atlantis" centers around characters named Ted Brautigan and Bobby Garfield. In King's book, "The Dark Tower: The Dark Tower VII," Ted is an ally to Roland's Ka-Tet. Bobby Garfield is Jake Chambers' "twinner."
Black House
Everything's Eventual
This collection, published in 2002, contains two novellas directly connected to the Dark Tower series. The First One, "Everything's Eventual", is the story of Dinky Earnshaw, a secondary character that becomes prominent in the seventh book. The second, "The Little Sisters of Eluria", is a sort of prequel to the entire series, describing a young Roland Deschain.
From a Buick 8
Minor connections
The House on Value Street
This unpublished and unfinished novel featured the first mention of Randall Flagg, here as Donald DeFreeze.
Cell
Late in the novel, the protaganists stumble across a half-assembled carnival, which includes a child's ride called "Charlie the Choo-Choo", a reference to the third and fourth books in the series.