Adam Clarke on 2 Timothy 4:11

Only Luke is with me - This was Luke the evangelist, and writer of the Acts of the Apostles, who was always much attached to St. Paul, and it is supposed continued with him even to his martyrdom.

Take Mark, and bring him with thee - This was John Mark, the sister's son of Barnabas, who, after having wavered a little at first, became a steady, zealous, and useful man; his name and conduct have been often before the reader. See the parallel passages.

For he is profitable to me for the ministry - Εις διακονιαν· For service; that is, he would be very useful to the apostle, to minister to him in his present close confinement. Some think that the apostle means his preaching the Gospel; but at this time, I should suppose, there was very little, if any, public preaching at Rome.