Bill Denbrough

In late fall of 1957, Bill has developed a severe cold, inhibiting him from attending school. While home, he constructed a paper boat for his younger brother Georgie to play with outside. Bill warns him to remain cautious of the unstable weather and tells his brother to be careful after Georgie kisses his older brother on the cheek. This would be the last time the two would ever see each other again. Not long after, George was slain by IT (in the form of a circus clown).

On the afternoon of last day of school, Bill and Edward "Eddie" Kaspbrak decide to build a dam in the Barrens but are confronted by the school bully Henry Bowers and his cronies Victor Criss and Belch Huggins who are in pursuit of Ben Hanscom. Bill and Eddie tell them they haven't seen him, and believing that they're lying, Henry pushes Eddie to the ground and breaks his nose while Henry destroys down their dam. Bill then tells them to back off and Henry, Belch, and Vic leave after losing interest in finding Ben. After his inhaler runs out, Eddie flies into panic and Ben appears just in time for Bill to leave them both to run to the pharmacy for Eddie. When Bill returns, Eddie introduces him to Ben who then shows them how to build a proper dam, Bill and Eddie are impressed by Ben's architectural knowledge.

During the second day of building the Dam, Richie Tozier makes his appearance along with Stan Uris . Richie brings out some Cuban cigars which Bill smokes happily while Eddie refuses because of his asthma. A police officer, Mr. Nell comes along and is shocked to see that they've blocked up the Dam. When Ben tearfully owns up to it, Bill vouches for Ben along the rest of the boys and they destroy the Dam. Despite his anger Mr. Nell praises Ben for his talent and warns the rest of the boys not go into the Barrens alone, telling them to go as a group.

Bill is amazed about hearing Ben and Eddie's stories and discusses it with Richie, where Bill expresses his deep seeded guilt over his role in Georgie's death, Richie consoles Bill, pointing out it he can hardly be blamed for trying to make his brother happy while he had the flu. This causes Bill to cry in relief and thanks Richie but warns him not to tell anyone he cried. Richie asks Bill to show him Georgie's photo album, so the two boys go inside Georgie's unnaturally cold room. Richie picks up the album and sees the dried blood from Bill's last encounter. They see one of the pictures moving, showing the old days of Derry. Bill and Richie see IT as Pennywise in the album and are terrified to see that Pennywise has Georgie's face. Bill, stricken, reaches out for the photo and Richie has to tug his hand out when Bill slices three of his fingers as they are sucked into the photograph.

Feeling more resolved, Bill, armed with his father's Walther PPK .380, travels down to one of the distant houses on Neibolt Street (where Eddie had encountered It in the form of the homeless leper under the house's porch) in pursuit of his brother's killer, whom he believed still lives there. Richie accompanies him to the house, though reluctantly and armed with sneezing powder. While searching around the deserted house, the two are ambushed and attacked by It, with Bill perceiving it as Pennywise the clown and Richie as the werewolf from "I Was a Teenage Werewolf".

The creature isn't affected by Bill's gun and grabs the boy as he's to escape through the window. Richie also grabs his friend and struggles with the monster. When Richie does an impression of Mr. Nell, IT is affected by the humor and releases Bill. Richie then throws the sneezing powder at the monster and successfully damages IT. The two manage to barely escape with Bill's trustworthy bike, Silver. When they are many blocks away, Richie, who had been scratched, collapses and so does Bill, and both burst into tears and hug each other.

Weeks after the near the near-death experience on Neibolt Street, the Loser's club gets bigger by welcoming Beverly Marsh into the fold. Beverly forms some feelings for Bill, during one calm afternoon down at the Barrens. Mike Hanlon meets the Losers while fleeing from Henry Bowers and his gang, Bill orders the group to pick up stones and the Losers drive the bullies away, Bill threatens Bowers telling him to stay away from the Losers and that the Barrens is theirs. Beverly welcomes Mike and Bill realizes "the circle is complete", Mike then takes out his dad's album of Old Derry to show and then the Losers (especially Stan) are terrified to witness IT threatening to "kill them all" through the Mike's Album. Stan is hysteric and Bill calms down, Bill tells the group that IT is scared now that they are all together and that can destroy the demon when they are united.

Once again down at the Barrens, Ben has used his architectural prowess to build a large wooden box in the ground which the Losers hide with a trapdoor. Inspired by Native Americans the Losers decide to make a campfire inside the hole. All seven sit inside and let them breathe in the smoke from the fire; Ben, along with Eddie, Beverly, and Stan, leave the hole, but Mike and Richie stay. The two boys witness IT coming to Earth on a meteorite that falls in Derry during prehistoric times and resting there. Before they suffocate, Bill and others pull Richie and Mike from the hole and they recount what they saw.

The Losers plan to kill IT and decided to melt down sliver into slugs using Bill's dad smelter and Ben's silver coins. The Losers discuss who will use the Slingshot against IT and Beverly outperforms everyone using the weapon. Then the group travel to Neibolt Street and go to the house where Eddie, Bill, and Richie were attacked. Now united as a group, they travel the house and experience the bizarre illusions that IT sends their way, as the house bends are distorts trying to separate them. Bill states to the group that "it's not real" and they're strong united. Once they get to the bathroom, IT appears to them in its Werewolf form. The beast tries to kill Beverly and then Bill but Ben protects them but gets slashed in the chest as a result. Beverly wounds IT with the slingshot and it escapes through the drain. Bill lends Beverly his shirt when hers get ripped and Bill starts forming some feeling feelings for her which Ben recognizes and feels passive jealously.

By the end of the summer of 1958, Bill had led the Losers into the Derry sewers, where they intended to confront and ultimately eradicate the terrorizing creature that had murdered his younger brother the year before. Deep under the city, they eventually come across the hellish beast’s fortress. In the decisive attempt to destroy IT, Bill engaged in the “Ritual of Chud” (a tribal-based semantic that is supposedly used to repel “impure” spirits) with the demonic entity. With the help of the “Turtle” (a guardian-like supernatural being that had originated from the same universe IT came from), he ultimately succeeded, defeating the paranormal demon (although it proved to be only a brief conquest as the ancient terror would resurface twenty-seven years later). Following IT’s alleged demise, the Loser’s began to lose their sense of connectivity with one another. Upon leaving the sewers, Bill formed a divine blood oath with the others, where they would promise to unite again if IT was ever to return.