Titus Avidius Quietus (died by 107 AD) was a Roman senator active during the reigns of the emperors Domitian, Nerva and Trajan.

This petition, recorded in an inscription set up in Rome, led Birley to suspect that Quietus "was chosen as patron of Deultum because he was legionary legate at the time the men were settled, i.e. in 82.

[3] Following Domitian's assassination in 96, Quietus spoke in defense of Pliny the Younger before the Senate when the latter attempted to obtain revenge for the Stoic leader Helvidius Priscus.

The nephew of the older Quietus, Gaius Avidius Nigrinus, consul in 110, was put to death at Faventia in 118 on charges of conspiring against Hadrian.

However Nigrinus' daughter, Avidia, married the man Hadrian later was to adopt and make his successor, Lucius Ceionius Commodus.