The Katechon (from Greek: τὸ κατέχον, "that what withholds", or ὁ κατέχων, "the one who withholds") is a biblical concept which has subsequently developed into a notion of political philosophy.

The term is found in 2 Thessalonians 2:6-7 in an eschatological context: Christians must not behave as if the Day of the Lord would happen tomorrow, since the Son of Perdition (the Antichrist of 1 and 2 John ) must be revealed before. Paul then adds that the revelation of the Antichrist is conditional upon the removal of "something/someone that restrains him" and prevents him to be fully manifested. Verse 6 uses the neuter gender, τὸ κατέχον; and verse 7 the masculine, ὁ κατέχων.

The interpretation of this passage has raised many problems, since Paul does not speak clearly.

The following interpretations has been given : the katechon is

The Roman Catholic and Eastern Orthodox traditions consider that the Antichrist will come at the End of the World. The katechon, what restrains his coming, was someone or something that was known to the Thessalonians and active in their time: "You know what is restraining" (2:6). As the Catholic New American Bible states, "Traditionally, 2 Thes 2:6 has been applied to the Roman empire and 2 Thes 2:7 to the Roman emperor ... as bulwarks holding back chaos (cf Romans 13:1-7)..."[1] However, some understand katechon as the Grand Monarch or a new Orthodox Emperor, some as the rebirth of the Holy Roman Empire (see, e.g., Ultimate Things: An Orthodox Christian Perspective on the End Times, Dennis Eugene Engleman, Conciliar Press, 1995).