The purpose of this chapter is to examine the consonant inventories of the Transeurasian languages from a comparative perspective. The chapter begins with a discussion of the reconstruction of the consonant inventory of Proto-Transeurasian, the hypothetical proto-language from which the Turkic, Mongolic, Tungusic, Koreanic, and Japonic languages are descended. Two competing reconstructions for the Proto-Transeurasian consonant system are evaluated, namely one that posits a two-way voicing contrast in the series of stops and affricates and one that posits a three-way contrast. Thereafter, the individual branches are considered in turn. The chapter ends with a discussion of root-structure patterning in Proto-Transeurasian.