Killed by Piccolo fighting Raditz

Killed when Cell self-destructed

Piccolo

Killed by Nappa

Killed when Maijn Boo destroyed Earth

Gohan

Killed when Majin Boo destroyed Earth

Vegeta

Killed by Frieza

Self-destructed to kill Majin Boo (failed)

Krillin

Killed by Frieza

Killed when Majin Boo destroyed Earth

Tien

Killed by Nappa

Killed when Majin Boo destroyed Earth

Yamcha

Killed by a Saibaman

Killed by Majin Boo

Chaouzu

Self-destructed to kill Nappa (failed)

Killed when Majin Boo destroyed Earth

Future Trunks

Killed by Perfect Cell

Goten

Killed when Majin Boo destroyed Earth

Trunks

Killed when Majin Boo destroyed Earth

Chi-Chi

Turned into an egg and stepped on by Majin Boo

Killed by Piccolo (with Goku & Gohan's help)

The Saibamen

1 self-destruct, 1 killed by Vegeta, the rest by Krillin

Nappa

Beaten by Goku, then killed by Vegeta

Kui, Dodoria & Zarbon

Killed one by one by Vegeta

Guldo

Killed by Vegeta

Beaten after death by Chaozu

Recoome

Killed by Goku

Beaten after death by Tien

Burter

Killed by Goku

Beaten after death by Yamcha

Jeice

Killed by Vegeta

Beaten after death by Yamcha

Captain Ginyu

Trapped in frog body (does not die in series)

Frieza

Ripped to shreads by Goku and self

Killed by Future Trunks

The Spice Boys

Killed one by one by Gohan

Garlic Jr.

Trapped in the dead zone by Gohan (twice)

Dr. Gero/Android 20

Destroyed by Android 17

Android 19

Destroyed by Vegeta

Android 18

Absorbed by Cell (then spit out)

Android 17

Absorbed by Cell

Android 16

Destroyed by Perfect Cell

Cell

Self-destructed to destroy Earth (failed)

Regenerated and killed by Gohan

Yamoo

Killed by Vegeta

Supopovitch

Killed by Goku

Dabura

Killed by Gohan

Majin Boo