Trophimus was a fellow worker of Paul. He accompanied Paul during Paul's third journey.
Acts 20:4And there accompanied him into Asia Sopater of Berea, and of the Thessalonians, Aristarchus and Secundus; and Gaius of Derbe, and Timotheus; and of Asia, Tychicus and Trophimus.
When Paul was in Jerusalem with Trophimus, the Jews misunderstood that he, being a Gentile, had entered the temple and defiled it.
Acts 21:29(For they had seen before with him in the city Trophimus an Ephesian, whom they supposed that Paul had brought into the temple.)Acts 21:30And all the city was moved, and the people ran together: and they took Paul, and drew him out of the temple: and forthwith the doors were shut.
In 2 Timothy, it is stated that he was sick.
2 Timothy 4:20Erastus abode at Corinth: but Trophimus have I left at Miletum sick.