Waimanu is a genus of early penguin which lived during the Paleocene, soon after the Cretaceous–Paleogene extinction event, around 62–60 million years ago.

Waimanu was a very early member of the Sphenisciformes, the order that includes modern penguins.

[1] It may have resembled a flightless loon or diver in body shape, and possibly the great auk in its manner of locomotion.

One species is known, W. manneringi, named for Al Mannering who found and collected the holotype specimen.

[2] The discovery of Waimanu provided evidence for debate about whether the radiation of modern birds, Neoaves, took place before the extinction of the non-avian dinosaurs or extremely rapidly immediately after.