Gray Bowser Statues are statues that look a lot like the Koopa King and first appeared in Super Mario Bros. 3. There are Golden Bowser Statues too.
The Gray Bowser Statue will just stand there shooting lasers at Mario should he get too close, and may not be defeated. It also appeared in Super Mario World where it did the same thing.
Lately it has appeared in Mario Kart 64 and Mario Kart: Double Dash!! in the Bowser's Castle courses. In Mario Kart 64, the Bowser Statue would just stand there shooting fire that would not hurt anyone. However in Mario Kart: Double Dash it could move, and it would shoot fire that could hurt anyone.
Other Gray Bowser Statues are not a live and do not move, like the ones in New Super Mario Bros..
They also appeared in Mario Party 2 and Mario Party 8-in both games they appear in mini-games where they need to get hit. They are non-living too.