The São Tomé Giant Sunbird is confined to São Tomé Island. It has dark blue-purple sheen and a long tail, and searches forest for nectar and small prey.
It has dark blue-purple sheen and a long tail; the vent is yellow in a species profile. Older accounts describe blue or bronze feather edges and white tips on outer tail feathers in males.
It mainly uses forest and is often recorded in middle- and higher-elevation forest on São Tomé. It probes leaves, flowers, bark, and epiphytes and visits flowering trees for nectar.
An extinction-risk assessment has not been added yet.