In taxonomy, Roseobacter is a genus of the Rhodobacteraceae. The Roseobacter clade falls within the {alpha}-3 subclass of the class Alphaproteobacteria. The first strain descriptions appeared in 1991 which described members Roseobacter litoralis and Roseobacter denitrificans, both pink-pigmented bacteriochlorophyll a-producing strains isolated from marine algae. The role members of the Roseobacter lineage play in marine biogeochemical cycles and climate change cannot be overestimated. Roseobacters make up 25% of coastal marine bacteria and members of this lineage process a significant portion of the total carbon in the marine environment. Roseobacter clade plays an important role in global carbon and sulphur cycles. It can also degrade aromatic compounds, uptake trace metal, and form symbiotic relationship. In term of its application, Roseobacter clade produces bioactive compounds, has been used widely in aquaculture and quorum sensing.

The Rhodobacteraceae are a family of Pseudomonadota in the order Rhodobacterales within the alpha subgroup. Like all Pseudomonadota, they are gram-negative. It contains chemoorganotrophs and photoheterotrophs bacteria. Many occur in aquatic habitats.