Luke
Acts 18:12ESV·traditional attribution

But when Gallio was proconsul of Achaia, the Jews made a united attack on Paul and brought him before the tribunal,

John Calvin Reformed @genevareformer

12. When Gallio. Either the change of the deputy did encourage the Jews to wax more proud and insolent, as froward men use to abuse new things that they may procure some tumult, or else hoping that the judge would favor them, they brake the peace and silence at a sudden, which had continued one whole year.

Matthew Henry Presbyterian @wholebiblehenry

We have here an account of some disturbance given to Paul and his friends at Corinth, but no great harm done, nor much hindrance given to the work of Christ there. I. Paul is accused by the Jews before the Roman governor, Act 18:12, Act 18:13. The governor was Gallio, deputy of Achaia, that is, proconsul; for Achaia was a consular province of the empire.

Commenting on Acts 18:12-17

John Gill Reformed Baptist @doctorgill

And when Gallio was the deputy of Achaia,.... This province, which was now become a Roman one, Pliny the younger (q) calls true and mere Greece; it went by the name of Aegialus (r), and now it is called Livadia: it has on the north the country of Thessaly, and on the west the river Acheloo, or Aracheo, on the east the Aegean sea, and...