The densely populated homeworld of the Denobulans and of Enterprise's chief medical officer, Phlox.
Denobula is the home planet of the Denobulans and of Doctor Phlox. It is the base of the Denobulan Science Academy, and through the Interspecies Medical Exchange the human doctor Jeremy Lucas serves there while Phlox serves aboard Enterprise, as described in their letters in Dear Doctor.
Phlox often speaks of his world and his large extended family. In The Breach, a request from the Denobulan Science Academy sends Enterprise to rescue geologists from a hostile planet, while the arrival of an Antaran patient recalls the long conflict between Denobula and the Antarans.