Ice Beam

The Ice Beam is one of Samus's beam weapons that appears in all Metroid games except for Metroid Prime 2: Echoes, Metroid Prime Hunters, and Metroid Prime 3: Corruption. It fires a potent beam that has the power to freeze most enemies.

When frozen, certain enemies can be shattered with missiles (or charged shots in the Prime series). It's commonly used to combat Metroids as it exploits their weakness to low temperatures.

In Metroid Prime
The Ice Beam is a slow-firing interchangeable Beam upgrade to Samus' arsenal. Upon impact with a solid surface, the shot will freeze into a small fragment of ice and then shatter. When the Ice Beam is charged up, the Ice Beam will not only create a larger fragment of ice upon impact, but it will also freeze various enemies in their place. The Ice Beam is able to open White Doors. The 10 Missile Beam Combo for the Ice Beam is the Ice Spreader, which is a missile that upon impact, with its concussive blast, releases a rapidly spreading sheet of ice upon the impact surface. Such a weapon is highly effective against enemies of the flying variation or those that attack/move in swarms. A glitch in the game allows the player to get it before fighting the Flaahgra which allows the player to perform more glitches.

Curiously in the New Play Control! version of the game, the Arm Cannon does not freeze over when charged. Seeing as a similar thing happens to the Dark Beam when charged, it is unknown if that action will be removed from the Echoes release too.

In other games
Samus has the power to stand on frozen enemies in all of the 2D games. This is usually crucial at some point in the games.

In Metroid Fusion, the Ice Beam was thought to be incompatible with the Fusion Suit by the federation, because the Metroid Vaccine gave Samus a vulnerability to ice, so she did not recover it until near the end of the game from the SA-X. However it appears that not all of its power was absorbed as the SA-X's could damage, drive back, and stun the Omega Metroid and Samus's could only do the first two. Before that point, freezing was done with the Ice and Diffusion Missiles. The Ice Missiles replaced the Ice Beam in Metroid Prime 3: Corruption, as well. Some of the characteristics of the Ice Beam are taken over by the Dark Beam in Metroid Prime 2: Echoes and the Judicator in Metroid Prime Hunters.