The author considers the possibility of studying a specific historical personality by the methods of pragmalinguistics based on the correspondence of I. V. Grozny in the aspect of the author's speech dominance. The research material is the personal letters of the tsar, the methods were the diagnosis of the speaker's speech personality by his speech behavior. This article proposes the use of pragmalinguistics methods that allow describing the speech portrait of Ivan the Terrible based on his use of grammatical and textual categories in correspondence with other monarchs and important historical figures. Thus, the subject of the study is the speech behavior of a historical figure in diachrony by the methods of pragmalinguistics. To date, the reconstruction of the linguistic appearance of the tsar has mainly been carried out on the basis of traditional methods of analyzing lexico-semantic and stylistic components and comparing them with a social portrait. The connection between language and thinking, which is considered by the example of correspondence, allows us to believe that the basic pragmalinguistic principles remain unchanged in the language for a long time and the functional abilities of grammatical categories to be associated with personal preferences remain despite linguistic variability. The conducted experiment of speech diagnostics allows the authors to study the aspect of the speech dominance of the personality of Ivan the Terrible at the level of linguistic pragmatics.