Malcolm Guthrie (10 February 1903 – 22 November 1972), professor of Bantu languages, is known primarily for his classification of Bantu languages (Guthrie 1971). The classification, though based more on geography than relatedness, is nonetheless the most widely used.
The magnum opus of Guthrie is Comparative Bantu which appeared in 4 volumes published in 1967 (volume 1), 1970 (volumes 3 and 4), and 1971 (volume 2). The 4 volumes provide not only a genetic classification but also a reconstruction of Proto-Bantu as the Proto-language of the Bantu language family. For his reconstruction, Guthrie drew data from 28 so-called 'test languages' that were picked more or less randomly. It has been argued, for example by Wilhelm Möhlig, that this renders his reconstruction unreliable, since the reconstructed forms, and hence the genetic tree, would be different if one changes the selection of languages.
Guthrie also published extensively on a wide range of Bantu languages, including Lingala, Bemba, Mfinu, and Teke.