We describe three novel species of piroplasms, each from a distinct host species within the Macropodoidea, in Western Australia; namely, Setonix brachyurus (Quoy & Gaimard, 1830), Macropus fuliginosus (Desmarest, 1817) (Macropodidae) and Bettongia penicillata (Gray, 1837) (Potoroidae). The light-microscopic appearance of organisms in blood films was typical of the Piroplasmida. Phylogenetic analyses of partial 18S rRNA gene sequences revealed that isolates from three marsupial species form reciprocally monophyletic clades within the Theileriidae, and each have a relatively high level of divergence (3.6 to 7.4%) from each other. The distinct molecular differences indicate these organisms should be regarded as separate, novel species which we designate Theileria brachyuri sp. nov., Theileria fuliginosa sp. nov., and Theileriapenicillata sp. nov.