Frieza and his Clan

[Cacarot]

What do we know about them? Are Frieza, Cold and Cooler the only ones left of their kind? What is the extent of their empire?

[Fox666]

Going by the manga, we only know Freeza and Cold. And in an interview Toriyama mentioned they are probably a hybrid race and there aren't many of them, and that Cold's father was the first mutant among them.

The 5th movie introduced Coola, and in Dragon Ball Heroes we have Chilled and a few generic unnamed characters of the same species. Interesting, it seems Dragon Ball Heroes label them as "Freeza's clan" while I suppose the head of the family is Cold, not Freeza.

[Cacarot]

Based on your answer, it seems like Freeza and his clan are basically the Yodas of dragonball. Really powerful and important to the story but next to nothing on their backstory. I also could imagine Lucas giving a similar response to that of Toriyama.

[Fox666]

I wouldn't call them "important".

Ginyu mentioned that the Tokusentai are mutants. Probably Freeza and Cold aren't different, someone was lucky to born with a great power and generated a very few offspring.