Theodore of Octodurum

; 4th century) is the first known bishop of Octodurum, Alpes Poeninae province (present-day Martigny, Valais, Switzerland).

[1] He is known to have participated in the Council of Aquileia in 381, his presence being preserved on the attendance list as Theodorus Episcopus Octodorensis.

He was also one of the signatories of a letter addressed by the Synod of Milan to Pope Siricius early in 390, informing him of their condemnation of the monk Jovinian and his followers.

Aloys Lütolf placed the beginning of his episcopate in the 340s, which would amount to a reign of more than forty years.

[1] It is possible that three distinct historical bishops with the name Theodulus or Theodorus are venerated as a single saint.