As a child, his best friends were Big Bill Denbrough, Stan "the Man" Uris, and Eddie Kaspbrak. He was also friends with Beverly Marsh, Ben Hanscom, and Mike Hanlon. Like the others in the Losers' Club, he looked up to Bill. He also thought Beverly was pretty, but only perceived her as if she was the same as any other male friend. He also often teases the other Losers, especially Eddie, calling him "Eds" and "cute" against his protests.
He wore thick black glasses and had huge front buck teeth which earned him the name "Bucky Beaver" by others in his school, though he was later dubbed "Trashmouth" by the Losers due to his foul language and loud mouth that often got him into trouble. The other Losers often used the phrase "Beep beep, Richie" whenever they needed to silence him. Although Richie misbehaved a lot in school, he received straight A's in school besides his grades in behavior. Before Richie joined the Losers' Club, Bill noted seeing him insulting Henry Bowers and his gang, resulting in him getting chased and beaten until he cried.
Richie is known for his hobby of doing Voices and impersonations, although when he is younger most of them were awful and sounded much like himself.
Richie's father, Wentworth, was a dentist and often disregarded what he viewed as Richie's foolishness. He would trick him into doing chores, and even called him stupid. Richie's mother, Maggie, was kind and attempted to understand her son, but was unable to. She even goes so far as to wish she had another child, perhaps a daughter, who she would be able to better understand and relate to.
(In 2017 Film) Richie's mother is an alcoholic and is often neglected by his parents. Because of this, he uses his loud and obnoxious personality as a coping mechanism and as a means for attempting to receive more attention.
The Smoke Hole
Richie and Mike Hanlon were the only two who were able to survive Ben Hanscom's smoke hole, witnessing the coming of It to the earth thousands of years ago.
Encounter with It
Richie had his personal encounter with It after running away from Henry and the other bullies. He rested on a bench, tired from running from the group, when the Paul Bunyan statue near him came to life and began to chase and attack him. However, unlike the other Losers and their encounters with It, Richie did not believe that what he had witnessed was real. He believed it was a dream, and did not tell the others about it when they were all confessing their own encounters.
Another encounter that Richie has with It is after Bill tells the Losers what he had seen when he had opened Georgie's photo album, how it had bled and how Georgie had winked at him. Richie told Bill that he wanted to see it for himself, and reluctantly Bill agreed. Before this encounter, Richie had not taken It or even the concept of death seriously-- perhaps he had not thought about it at all. However, after stepping into Georgie's room, the reality of death hits him for the first time in his life. He begins to understand that anyone could die at any time or at any age, which causes him to panic. When he and Bill finally open the book, they witness an image of Derry many years ago, and they see boys that look identical to themselves in the picture as well. Bill accidentally touches the page and his fingers nearly go into the picture. When he pulls them out, they are covered with deep cuts. This is truly the first time Richie understands the reality of It.
Later, Richie goes with Bill into the house on Neibolt Street, the one where Eddie saw his encounter with it (the leper). In the house, he sees It take form as the Teenage Werewolf from the movie I Was a Teenage Werewolf that he had seen at the Aladdin Movie Theater days before. The Werewolf was wearing a varsity jacket with "Richie Tozier" embroidered on the chest pocket.
As an adult, he is a famous radio DJ, going by Rich "Records" Tozier living in Beverly Hills. Richie had several failed relationships with women, but had never gotten married. The voices that he constantly practiced as a kid improved greatly and became highly revered and loved, making a lot of money off the notoriety of his comedic voices. He began wearing contact lenses as an adult as well.
Along with the other Losers, he returns to Derry after receiving a phone call from Mike Hanlon alerting him that It had returned. They all go into the sewers and Richie and Bill perform the Ritual of Chud as they did as kids, to put a stop to It once and for all.
In the sewers, Eddie loses his arm and dies. Richie has the most difficult time dealing with Eddie's death since they were so close. Richie is the last person Eddie talks to before dying, stroking Richie's face with his hand and telling him, for the last time, not to call him "Eds" as he always had. At first, Richie refuses to leave his body in the sewers, insisting it was too dark and Eddie would not want to stay down there. After he is forced to leave Eddie's body, he kisses Eddie on the cheek before leaving.
Appearance in 11/22/63
Richie briefly appears in the novel 11/22/63 as well, when the main character Jake Epping arrives in Derry and sees him dancing with Beverly. Jake (using the alias George Amberson) asks the two if they know about the Dunning children. He notices the special relationship they have: not romantic, but that of two friends that had gone through a lot together. He notes they were the only thing that felt good about Derry, and helps them practice dancing.
[In his Pancho Vanilla voice] Doesn't smell like kaka to me, señor!
"Go blow your dad, you mullet-headed asshole!"
What the hell's gray water?
"Do you gotta be a virgin to see these things? Cuz'
"I haven't seen shit."
"News flash, Ben, School's Out for Summer." 
I didn't hear that! I didn't!
Richie Tozier's the name, and doing voices is my game.
This here is Stan the Man Uris, he's a Jew, which means he's very smart, and says "Oi" alot!00:12, September 16, 2017 (UTC)00:12, September 16, 2017 (UTC)00:12, September 16, 2017 (UTC)00:12, September 16, 2017 (UTC)
Help! Down in the basement! There's a werewolf.
Oh, come on! Not the Paramount, you slimeballs! Where are the people of this city supposed to get their culture?!