Holly Sykes is the central protagonist and one of the narrators of The Bone Clocks. She is first introduced as a rebellious 15-year-old girl living in Gravesend, Kent. She has three siblings, Brandon, Sharon, and Jacko, and is often at odds with her mother, Kath. The novel opens with Holly leaving home after an argument with Kath over Holly’s illicit relationship with an older man named Vinny Costello. Holly leaves to prove that she can successfully live on her own.

Holly is partially defined by her psychic abilities. In childhood, she heard voices and seemingly hallucinated a strange woman named Miss Constantin. In reality, Holly was exhibiting signs of psychic potential; Constantin was preparing her for consumption by the Anchorites. To save Holly from this danger, Marinus rendered Holly’s psychic capabilities inert, making her energy unpalatable to the Anchorites. Holly’s psychic potential reactivates in adulthood; in Part 3, she experiences a vision that allows her husband, Ed Brubeck, to locate their missing daughter, Aoife. At Ed’s suggestion, Holly writes a memoir about her childhood experiences entitled The Radio People.

Holly is traumatized by the sudden disappearance of her beloved youngest brother, Jacko, at the end of Part 1.