The song "Only Child" by the Glee Cast is a cover of the original song by Tierra Whack. It was featured in Season 6, Episode 3 ("Jagged Little Tapestry") of the TV series "Glee." In this episode, the New Directions perform various songs that celebrate their differences and individuality. "Only Child" is known for its catchy and upbeat vibe, showcasing the diverse talents of the Glee Cast members. The song is a reflection of the show's theme of embracing uniqueness and celebrating individuality through music.