William Rennie (1884–1952) was a Scottish classical scholar who produced the Oxford Classical Text of Demosthenes in three volumes (1921–1931). His edition replaced the 19th-century OCT and provided a more rigorous treatment of the manuscript tradition. Rennie was known for his careful, methodical approach to textual criticism and his thorough collation of the principal Demosthenes manuscripts.

Rennie's OCT of Demosthenes (3 vols., 1921–1931) was the standard critical text for much of the 20th century. Like all OCT editions, it provides a clean text with a selective apparatus criticus at the foot of each page, recording the most important manuscript variants and conjectures. Rennie's approach is moderately conservative, preferring the transmitted text where defensible. For the most studied speeches (notably the Crown speech), Rennie's text has been supplemented or supplanted by more recent commentaries with their own textual discussions, but for the Demosthenic corpus as a whole his OCT remains the most convenient critical edition.