Moses
Exodus 7:12ESV·traditional attribution

For each man cast down his staff, and they became serpents. But Aaron’s staff swallowed up their staffs.

John Calvin Reformed @genevareformer

12. For they cast down every man. The number of the magicians is not expressed; and although Paul names two, Jannes and Jambres, C. has Mambres, the reading of the Vulgate. (2 Timothy 3:8,) it is probable that they were not the only ones, but the chief, and, as it were, the ringleaders. But I will not dispute this questionable point.

Matthew Henry Presbyterian @wholebiblehenry

The first time that Moses made his application to Pharaoh, he produced his instructions only; now he is directed to produce his credentials, and does accordingly. 1. It is taken for granted that Pharaoh would challenge these demandants to work a miracle, that, by a performance evidently above the power of nature, they might prove their commission from the God of nature.

Commenting on Exodus 7:8-13

John Gill Reformed Baptist @doctorgill

For they cast down every man his rod, and they became serpents,.... That is, they seemed to be so, as Josephus (z) expresses it, but not really, in which he is followed by many; though some think that the devil assisted in this affair, and in an instant, as soon as the rods were cast down, removed them and put real serpents in their room...