John of Ibelin (c. 1179 – 1236), called the Old Lord of Beirut, is a powerful crusader noble in the 13th century, one of the best known representatives of the influential Ibelin family.

The son of Balian of Ibelin and Maria Comnena, Queen consort of Jerusalem, he has close ties with the nobility of both Cyprus and Jerusalem, since he is the half-brother of Queen Isabella I of Jerusalem.

Before he is 20, he is appointed constable of Jerusalem, and a few years later becomes lord of Beirut, where he rebuilds the city after Saladin's conquest, and establishes the grand Ibelin family palace.

He serves as regent for two of his young relatives, Isabella's daughter Maria of Montferrat from 1205 to 1210, and then Henry I of Cyprus from 1228 until Henry comes of age in 1232.

John is known as a principled man, and is seen as the natural leader of the Christian barons in the Holy Land.

He resists the power-seeking of Frederick II, Holy Roman Emperor, in Cyprus, and opposes the imperial forces until Henry comes of age.