Race: Android
Planet Of Origin: Earth
Average powerlevel: 18,000
Strongest in series: Super Android 17
Useful Techniques: Energy absorb,
Info: The Androids were created by Dr.Gero of the Red Ribbon Army. The Androids were originally Human, but was scientifically enhanced to created the perfect fighters. The Androids had minds of their own and #17 killed his creator Dr.Gero.
Characters in series: #08, #13, #14, #15, #16, #17, #18, #19, #20, Cell, Cell Jr, Super 13, Super 17.

Race: Changelings/Icerz
Planet Of Origin: Unknown
Average powerlevel: 2,500,000
Strongest in series: Koola
Useful Techniques: Tranformation, Death Ball,
Info: The changelings are an evil race, and have the ability to transform at will. This race is asexual.
Characters in series: Frieza, King Kold, Koola

Race: Dragons
Planet Of Origin: Namek?
Average powerlevel: Unknown
Strongest in series: li Shenlong
Useful Techniques: Unknown
Info: The draogns were originally created by the Nameks, in order to grant wishes to the finder of all 7 dragonballs. In GT we meet the Evil Dragons. They were incredibly powerful and put up a great fight against SSJ4 Goku and Vegeta.
Characters in series: Shenlong, Porunga, li shenlong, San Shenlong, Suh Shenlong, Chii Shenlong, Ryan Shenlong, Ryuu Shenlong, Uh Shenlong

Race: Humans
Planet Of Origin: Earth
Average powerlevel: 1,000 (with KI), 5 (without KI)
Strongest in Series: Krillin
Useful Techniques: KameHame Ha, Solar Flare, Zanzoken
Info: Humans are somewhat a peaceful race in DB. Most do not posses the power of KI. Only a few choose to fight. One of the Masters of Martial Arts on Earth is Master Roshi. He teaches many people in DB such as, Goku, Krillin, Tien, Yamcha and Chouzu. Humans aren't very strong but have some nice techniques.
Characters in series: Krillin, Yamcha, Tien, Chouzu, Master Roshi, Bulma, Chi Chi, Dr. Briefs, Mrs. Briefs, Marron, Mr. Shoe, Dr. Gero, Hercule/Mr.Satan, Videl, Announcer, Baba, lots more not so important ones.