In Galatians 2:9, which three men were "reputed to be pillars"?

Answer: James, Cephas and John

James, Cephas, and John, reputed to be pillars, gave Paul and Barnabas the right hand of fellowship.

“And recognizing the grace that I had been given, James, Cephas, and John—those reputed to be pillars—gave me and Barnabas the right hand of fellowship, so that we should go to the Gentiles, and they to the circumcised.”— Galatians 2:9 (BSB)