The first name of Mike and Nancy Wheeler’s youngest sibling in Stranger Things is Holly.
Holly Wheeler is the youngest child of Karen and Ted Wheeler, making her the younger sister of both Nancy and Mike. She appears from the first season as a small but observant member of the Wheeler family. Although she is much younger than the main teenagers, Holly occasionally notices strange events in Hawkins before her parents fully understand what is happening.
The character is easy to confuse with other girls in the series. Karen is Holly’s mother, Sara was Jim Hopper’s daughter, and Erica Sinclair is Lucas Sinclair’s younger sister. Holly is played by twins Anniston and Tinsley Price during the first four seasons, a casting choice used for the very young role. In season 5, the role was recast with Nell Fisher and Holly received a substantially larger part in the story.