Titus Sempronius Blaesus is a fictional person encountered in H. P. Lovecraft's story The Shadow out of Time (1934-35).

Titus was a Roman quaestor who lived during the the times of Roman dictator Lucius Cornelius Sulla, sometimes between 82 BC and 75 BC. He was the victim of a mind transfer with a member of the Great Race of Yith, and was sent back approximately 150 million years, where he met Professor Nathaniel Wingate Peaslee, the narrator of the story.