Other forms: panelists
If you're a member of a group that's officially (sometimes publicly) discussing a specific subject, you're a panelist.
Most panelists are either experts in the subject being discussed, or people whose lives are affected by related issues, developments, or changes. A group of panelists is called a panel, which comes from the Old French, in which it means "piece of cloth," and an Anglo-French legal meaning, "piece of parchment listing jurors." Panelist is an American English invention from about 1950.