Joyce Byers’s younger son in Stranger Things is Will Byers.
Will disappears while cycling home in the opening episode, “The Vanishing of Will Byers.” His disappearance launches the series’ central mystery and brings together his mother Joyce, police chief Jim Hopper, and his friends Mike, Dustin, and Lucas.
Will is the younger brother of Jonathan Byers. He spends much of season 1 trapped in the Upside Down, while Joyce and Hopper search for him in Hawkins. Although he returns home, his connection to the Upside Down continues to affect later seasons.
The character is played by Noah Schnapp. Will’s childhood friendship with Mike, Lucas, and Dustin is the foundation of the original group, and his experiences also shape the supernatural mythology of the show.