Aglaocetus is a genus of extinct baleen whales known from the Miocene of Patagonia, the US Eastern Seaboard, Japan and the Low Countries.

It was once considered a member of Cetotheriidae along with many other putative cetotheres, but was recently recognized as representing a distinct family from true Cetotheriidae.

There are three currently recognized valid species: Aglaocetus moreni, A. latifrons, and A.

[1][2][3] The type species, Aglaocetus moreni, was originally described as a species of Cetotherium, but later recognized as generically distinct from the latter.

[4] "Aglaocetus" patulus, described from the Calvert Formation by Remington Kellogg in 1968,[5] was recovered by Bisconti et al. (2013) in a different phylogenetic position than the Aglaocetus type species.