Evangelism is not mentioned in the New Testament as a spiritual gift but the office, or role, of the evangelist is listed in Ephesians 4:11-12. Saying that God gave these people to the church implies that there is a spiritual empowerment that they carry. While all Christians are expected to witness to Jesus, some people are especially gifted for that and, consequently, are especially effective.
Barnabas
Silas
Timothy