Thankfully, this is a relatively easy question to answer!
There are many good resources to learn the amazing stories of great missionaries of the past. There were certainly key pioneering persons who opened doors, overcame unimaginable circumstances, remained faithful despite terrible personal tragedies, and were used by God to bring the Gospel and plant local churches in previously unreached areas for God's glory.
The resources below will point you to highlight our most recommended biographies. Many are available in multiple ways via Internet search from educational, church, and missions websites. Take some time to let their stories soak into your soul, influence your thinking, stimulate your missions commitment, and challenge you to follow in their footsteps.