Landévennec (French pronunciation: [lɑ̃devɛnɛk]; Breton: Landevenneg) is a commune in the Finistère department of Brittany in north-western France.

Shortly before entering the roadstead of Brest, the river Aulne forms a bend around the Île de Térénez then the pointe de Pen Forn near Landévennec, where there is a 10 m (33 ft) depth of water regardless of the tide and with the high surrounding hills blocking the winds and thus keeping the water calm.

A naval station was first set up here around 1840 to house reserve fleet vessels and their crews (totalling nearly 200 sailors), and it was visited by Napoleon III and empress Eugénie during their August 1858 trip into Brittany.

However, having been emptied of nearly all its occupants, in August 2006 the graveyard took on three former breakwaters which would become Brest's "port du Château" and had been moved to allow expansion work to begin.

The cruiser Colbert and the Soviet-built hydrofoil ferry Kometa from the Penn-ar-Bed company (which provided summer services to Ushant) are now also based here.