Knoxx is a double-x spelling of Knox, a Scottish surname from the Gaelic cnoc meaning "round hill". Knox itself took off in America after Brad Pitt and Angelina Jolie chose it for their son in 2008, and the Knoxx spelling follows names such as Jaxx. In the United States Knoxx rose from number 4239 in 2015 to number 2099 among boys' names in 2025, its highest rank so far.