Philip and Stephen

One of the earliest, if not the earliest mission outside of Judea was carried out by Philip.

From the Bible Dictionary:

Philip: One of the seven; an evangelist (Acts 6:5; 21:8); preaches at Samaria, and to the Ethiopian eunuch (Acts 8); entertains Paul (Acts 21:8).

Stephen. One of the seven, “a man full of faith and of the Holy Spirit” (Acts 6:5); did great wonders and miracles (6:8); his disputations with the Jews (6:9–10); the charge brought against him and his trial before the Sanhedrin (6:11–15); his defense (7:2–53); his martyrdom (7:54–60) and burial (8:2); the scattering of the brethren that followed his death (11:19).

Stephen was one of the Christian martyrs of N.T. times, and is the first of whom we have record who proclaimed that the law of Moses was fulfilled in Christ and ought not to be continued in the Church. In this thing he foreshadowed the great work of Paul. In his speech before the Sanhedrin he justified his position by an appeal to Israelite history, showing that acceptable worship was offered to God before the law was given, and also pointing out that Israelites who lived under the law had persecuted the prophets whom God had sent. Paul was present when this speech was made (Acts 8:1; 22:20), and was probably influenced by it, though at the moment he was a consenting party to his death. A few years later he went on with the work that Stephen had introduced to him.