- See Jefferies for other articles with titles that contain, either by relationship or by coincidence, this character's surname.
Frederick William Jefferies was a Starfleet engineer responsible for designing the Jefferies tubes commonly found aboard Federation starships. He was the only son of Benjamin McDonald-Jefferies and Isobelle Krautman and a descendant of the 18th century Scottish Jacobites Seamus and Megan MacIntyre. (TOS novel: Home is the Hunter)
- Given the timeframe involved (his grandfather W.M. Jefferies married in 2137, meaning Frederick William was likely an adult in the waning days of the 22nd century), it is possible that Frederick William is an ancestor of William Jefferies. Note that Home is the Hunter consistently misspelled the name of the family as "Jeffries".