A founder member is someone who helped start a group or organization. They were there at the very beginning and played a crucial role in creating and establishing it. Full definition
Founder members of the league will struggle to survive. (justarsenal.com)
Many founder members have the necessary therapeutic experience and management skills but haven't set up a professional organisation from scratch before. (playtherapy.org)
That's two founder members of this site, and they've attracted many like - minded people to visit and offer their opinion. (arsenalarsenal.net)