Blastus was a 2nd-century leader of the Roman Montanists, a presbyter in Rome and a Quartodeciman, however likely born in Alexandria.
Some scholars have argued that the hostility of Pope Victor I against the Quartodecimans, was caused by Blastus' schism.
Blastus argued that Christians must keep Easter at the same time commanded in the Book of Exodus.
Irenaeus wrote a letter to Blastus called "on Schism" which is no longer extant.
They also drew away many of the Church to their opinion, each striving to introduce his own innovations in respect to the truth.