The Flamethrower is a weapon item that appears in Resident Evil.
When first recovered, it is absent of any ammunition, and it soon becomes evident that the racks that hold it are part of a locking-mechanism.
The first is found in the original Resident Evil (and the remake) by Chris Redfield in the underground area beneath the Spencer Mansion's courtyard. It can be used to fight the Black Tiger, destroying its offspring as well if used. The Flamethrower is also a puzzle key of sorts; it must be put into mounting racks in order to unlock certain areas, and, as such, is limited to a few very specific areas.
In the remake, a broken flamethrower is found in the tunnels where Lisa Trevor wanders. To leave the area, the player must pull a lever, then place the flamethrower into a rack before it retracts into the wall.
In Jill Valentine's scenario, if the player uses V-JOLT on Plant 42, they will view a special cutscene upon entering the plant room. The weakened plant will pick up Jill, and Barry Burton subsequently enters the room carrying a flamethrower. Barry then uses the flamethrower point blank, killing the plant.
In Resident Evil: Deadly Silence, Jill can also get the weapon during Remix mode, and it is used in a similar puzzle to the one in Chris' scenario.