Diplosian

Diplosians are a sapient humanoid species native to the G-class planet Diplos, in the Tau Ceti System.

Biology
Diplosians are humanoids with silver skin and can live for several millennia. Their metabolism is fundamentally different from that of Humans, and some foods cannot be consumed by them, including citric fruits such as lemons and grapefruit, avocados and some kinds of meat. Unlike Human blood, Diplosian blood can't be consumed by the Ogri.

Appearances

 * Doctor Who, season 16, "The Stones of Blood" (1978)