The red-billed oxpecker is a mutualistic passerine bird in the oxpecker family, Buphagidae. It is native to the eastern savannah of sub-Saharan Africa, from the Central African Republic east to South Sudan and south to northern and eastern South Africa. It is more widespread than the yellow-billed oxpecker in Southern Africa, where their ranges overlap.

Mutualism describes the ecological interaction between two or more species where each species has a net benefit. Mutualism is a common type of ecological interaction. Prominent examples are:the nutrient exchange between vascular plants and mycorrhizal fungi, the fertilization of flowering plants by pollinators, the ways plants use fruits and edible seeds to encourage animal aid in seed dispersal, and the way corals become photosynthetic with the help of the microorganism zooxanthellae.