Titus Tettienus Serenus was Roman senator of the first century.
He was suffect consul in the nundinium of July to August AD 81 as the colleague of Gaius Scoedius Natta Pinarius.
He is identified as the brother of Galeo Tettienus Petronianus, suffect consul in 76.
The only office Serenus is known to have held is governor of the imperial province of Gallia Lugdunensis, which Werner Eck has dated from the year 78 to the year 80, prior to his consulship.
An inscription found in Rome attests Serenus had been co-opted into the Sodales Augustales in the year 92.