1. Tychicus

“All my state shall Tychicus declare unto you, who is a beloved brother, and a faithful minister and fellowservant in the Lord: 8Whom I have sent unto you for the same purpose, that he might know your estate, and comfort your hearts.” (Col 4:7)

The word “servant” is διάκονος, (dee-ak’-on-os), which means a servant, minister, a waiter, servant, then of any one who performs any service, an administrator.

2. Onesimus

“9With Onesimus, a faithful and beloved brother, who is one of you.” (Col 4:9)

3. Epaphraus

“12Epaphras, who is one of you, a servant of Christ, saluteth you, always labouring fervently for you in prayers, that ye may stand perfect and complete in all the will of God. 13For I bear him record, that he hath a great zeal for you, and them that are in Laodicea, and them in Hierapolis.” (Col 4:12)

The words “labouring fervently” is ἀγωνίζομαι, (ag-o-nid’-zom-ahee), which means struggling, striving (as in an athletic contest or warfare); I contend, as with an adversary.

Conclusion: The Holy Spirit led Paul to salute others who were faithful servants like Barnabas, Luke and Aristarchus.
But please check out what he wanted to pass on to Archippus.

“And say to Archippus, Take heed to the ministry which thou hast received in the Lord, that thou fulfil it.” (Col 4:17)