Every member of Frieza’s race in DBZ

DBZ main continuity (anime/manga + DBZ TV specials)

1) Frieza — killed by Future Trunks (on Earth, after Trunks cuts him in half and finishes him with an energy blast).
2) King Cold — killed by Future Trunks (shortly after Frieza, on Earth).
Bardock note: In the DBZ TV special Bardock: The Father of Goku, Bardock does not defeat anyone from Frieza’s race; he’s killed by Frieza.

DBZ movies (official DBZ films; generally non-canon to the main story)

3) Cooler — killed by Goku (Cooler’s Revenge, sent into the Sun).
4) Meta-Cooler — defeated by Goku and Vegeta (The Return of Cooler, by destroying the Big Gete Star’s core/control, ending the Meta-Cooler system).

DBZ-era spin-off / what-if special (non-canon)

5) Chilled — defeated by Bardock (Episode of Bardock; Bardock overpowers and beats him in the past).