Corbenic or Corbin is the name of the Grail castle, the castle holding the Holy Grail, in the Arthurian literary tradition following the 13th-century Lancelot-Grail cycle and Thomas Malory's Le Morte d'Arthur. It is the domain of the Fisher King and the birthplace of Sir Galahad.
In Chrétien de Troyes' Perceval, the Story of the Grail, the first work to mention the Grail, the Grail castle is described somewhat differently than in later literature, and is given no name. In Wolfram von Eschenbach's Parzival, based on Chrétien, the Grail castle's name is Munsalväsche (rendereing Monsalvat, in medieval tradition associated with the name of Montserrat in Catalonia).
As befits the castle of the Grail, Corbenic is a place of marvels, including, at various times, a maiden trapped in a magically boiling cauldron, a dragon, and a room where arrows assail any who try to spend the night there. These wonders cause Sir Bors to name it the Castle Adventurous, "for here be many strange adventures" (Le Morte d'Arthur, book XI). Yet it can also appear quite ordinary: on an earlier occasion, according to the Lancelot-Grail, the same Sir Bors visited without noticing anything unusual.
(Perhaps conscious of this apparent contradiction, T.H. White in The Once and Future King treats Corbenic as two separate places: Corbin is the relatively mundane dwelling-place of King Pelles, while Carbonek is the mystical castle where the climax of the Grail Quest takes place.)
Corbenic has a town, and a bridge which Sir Bromell la Pleche swears to defend against all comers for a year, for love of Pelles' daughter Elaine (Morte, books XI–XII).
It is on the coast, or at least is mystically moved there for the purposes of the Grail Quest: Lancelot arrives at Corbenic by sea at the climax of his personal quest. Corbenic's seaward gate is guarded by two lions, aided by either a dwarf (Morte, book XVII) or a flaming hand (Lancelot-Grail).
It is unclear whether Corbenic is to be identified with the castle inadvertently levelled by Sir Balin when he delivers the Dolorous Stroke upon King Pellam (Morte, book II); if so, then Corbenic is in Listeneise (and is presumably rebuilt at some point). The Lancelot-Grail gives the name of its kingdom only as the 'Foreign Country'.