A Jewish political party who sympathized with (Mark 3:6; 12:13; Matt, 22:16; Luke 20:20) the Herodian rulers in their general policy of government, and in the social customs which they introduced from Rome. They were at one with the Sadducees in holding the duty of submission to Rome, and of supporting the Herods on the throne. (Comp. Mark 8:15; Matt. 16:6.)
Herodians
Few groups in the Gospels are named so briefly. The Herodians are mentioned only three times, and each time they are with Jesus’ opponents. In Mark 3:6 “the Pharisees went forth, and straightway took counsel with the Herodians against him, how they might destroy him.” In Matthew 22:16 and Mark 12:13 they are sent to “catch him in his words” with a question about taxes to Caesar. Scripture does not explain who they were, though the name suggests supporters of Herod’s family. What stands out is how people who disagreed with one another could agree about Jesus.
3 verses
Matthew
And they sent out unto him their disciples with the Herodians, saying, Master, we know that thou art true, and teachest the way of God in truth, neither carest thou for any man: for thou regardest not the person of men.
Mark
And the Pharisees went forth, and straightway took counsel with the Herodians against him, how they might destroy him.
And they send unto him certain of the Pharisees and of the Herodians, to catch him in his words.
From Easton's Bible Dictionary
Matthew George Easton, 1897