Power Beam

Samus Aran's Power Beam is her basic weapon. It comes with her Power Suit. The Power Beam does little damage to enemies, although it can easily kill the first ones in the games. It is Chozo technology that has probably been sent by the Chozo to other alien species. It is possible that the Power Beam is an ancient weapon as when she first used the up to date version on Mother Brain, the shields were immune to it but when Grey Voice attacked with a Century Old Weapon, it was able to penetrate as Samus's Beam does when she fights Mother Brain. It is a form of weaponry that replaced guns by having a good rate of fire and much more power. Over the course of the Metroid games, Samus has received various upgrades to her beam:


 * Long Beam
 * Spazer Beam
 * Wide Beam
 * Wave Beam
 * Ice Beam
 * Plasma Beam
 * Charge Beam
 * Dark Beam
 * Light Beam
 * Annihilator Beam
 * Nova Beam

Also, if Samus is wearing a certain Power Suit at a certain time, she can absorb things in her environment and transfer the power to her beam. This ability is demonstrated in Super Metroid, when she gains the powerful Hyper Beam to defeat Mother Brain, and in Metroid Prime and in Metroid Prime 2: Echoes when she acquires the Phazon Beam to defeat the Metroid Prime and Dark Samus, respectively.

In Metroid Prime Hunters, Samus's beam has a rapid-fire effect. It fires four shots at once, a fifth beam a second later, then begins to charge.

On a side note, in Metroid Prime Hunters: First Hunt the Power Beam used an ammunition system. This is the only game where it has done so. If the player ran out of ammo they would no longer be able to fire the Power Beam fully automatically, and would be unable to use Missiles. This may have been a product of the training hologram, however.

Cheat Beams
There are also three semi-functional glitch beams in Super Metroid. These can be accessed by collecting the required beams and using a glitch to activate Spazer and Plasma simultaneously.
 * Spacetime Beam, a combination of Ice, Spazer, and Plasma
 * Murder Beam, a combination of all beams available: Charge, Wave, Ice, Spazer, and Plasma
 * Chainsaw Beam, a combination of Wave, Spazer, and Plasma
 * Strange Beam, a combination of Wave, Ice, and Spazer.