The Laser Cannon, Core Cannon, Laser Turret, or a variety of other names is the prominent, vehicular protagonist in the Space Invaders series. However, unlike the invaders themselves, it does not appear as frequently, as games like Super Space Invaders '91 and Space Invaders Extreme opt for brand new designs, or at the very least do not feature it as center-stage.
The Cannon has taken on a variety of appearances since it's inception due to the vague nature of its original sprite. Some games interpret the vehicle as a grounded tank, while others view it as a fighter jet-like craft or a spaceship.
In the original game, the Cannon is slow in movement and firing rate, yet this doesn't apply to the vast majority of other games. The Cannon is known for a simple move-set, of just moving and firing, but many later entries give the cannon access to powerups.