Philemon 1:24 sends greetings from Mark, Aristarchus, Luke, and which other fellow worker?

Answer: Demas

Epaphras, Paul's fellow prisoner, sends greetings, as do Mark, Aristarchus, Demas, and Luke, his fellow workers.

“Epaphras, my fellow prisoner in Christ Jesus, sends you greetings, as do Mark, Aristarchus, Demas, and Luke, my fellow workers.”— Philemon 1:23-24 (BSB)