The katechon (from Greek: τὸ κατέχον, "that which 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. The author of Second Thessalonians then adds that the revelation of the Antichrist is conditional upon the removal of "something/someone that restrains him" and prevents him being fully manifested. Verse 6 uses the neuter gender, τὸ κατέχον; and verse 7 the masculine, ὁ κατέχων.
Since the author of Second Thessalonians does not explicitly mention the katechon's identity, the passage's interpretation has been subject to dialogue and debate amongst Christian scholars.
Common interpretations for the identity of the katechon include the government, the church, or the Holy Spirit. The last two interpretations are usually believed by Christians supporting a pretribulation rapture.