Parasite Queen

The Parasite Queen is the very first boss in Metroid Prime and, by extension, the first boss in the Prime trilogy. It is also, of course, the first Metroid boss to be fought in 3D. It is encountered on the Space Pirate Frigate Orpheon.

Overview
The Parasite Queen is a Parasite genetically enhanced by Phazon. The Parasites were some of the first species to be experimented on with Phazon by the Space Pirates. There were originally three Parasite Queens: two of them managed to break free from their stasis tanks and wreaked havoc in the Pirate Ship. The Space Pirates managed to kill one of them as it reached the Frigate's evacuation chamber, while the other reached the Reactor where it was later fought by Samus. After being sufficiently weakened, it fell into the reactor core, causing the ship to self destruct.

The third Queen that had remained in its tank awakened after the ship's reactor became unstable, though this one was immediately dispatched by Pirates as it broke through its glass. Also, the corpse of a heavily mutated parasite is seen within another tank, but this one most probably never reached Queen state, as it was still recieving phazon dosages at the time of its death. The two Parasite Queens that escaped are undoubtably the source of the Parasite infestation in the Frigate, as they must have given birth to an unknown number of offsprings, causing the Space Pirate personnel to evacuate.

The Battle
The Parasite Queen is a very straightforward boss. All Samus has to do is lock on the creature and fire at it. It will use shields to protect itself, though the shields have spaces in them which allow firepower to reach the Parasite Queen. The Power Beam, Charge Beam, and especially Missiles are very effective against the creature.

The Parasite Queen will open its mouth sometimes to roar at Samus. If Samus scans the Parasite Queen with the Scan Visor, she will learn this is its weak spot. She can now target the mouth, causing great damage to the Parasite Queen when she fires at it. Sometimes the shields will spin rapidly around the creature. Samus can either fire her Power Beam repeatedly to do some damage or charge her Power Beam and then fire it once the shields stop spinning. Once the Parasite Queen is destroyed, it damages the frigate's reactor core. Due to this incident, Samus has seven minutes to evacuate the frigate.

The Parasite Queen is often thought by fans to be one of the easiest bosses in the series, especially on Normal mode in the Metroid Prime Trilogy.

Metroid Prime Logbook Entry
Morphology: "Parasite Queen, parasite female genetically enhanced by unknown means. A weak spot has been detected in this creature’s mouth. Use your auto-targeting to acquire this new target! Scans indicate the presence of a potent mutagen, origins unknown. Creature exhibits the ability to fire weapon-grade blasts of energy from its mouth, a trait not present in the standard parasite genome. It appears the Pirates have begun a bioengineering program, with considerable results."

Trivia

 * It was originally intended for Samus to battle a much less restricted Parasite Queen; in other words, the Queen was not going to be fought within a container as seen in the final version of the game. This is shown in Metroid Prime's very first trailer, with the boss having much more freedom for movement such as running across the room and climbing on walls.
 * In Metroid Prime 3: Corruption, mutilated and heavily degraded Parasite Queen corpses can be found in an elevator in west SkyTown.
 * In Super Smash Bros. Brawl, the Parasite Queen appears in the background of the stage Frigate Orpheon. Her theme music is one of the songs that plays on the stage.
 * The Parasite Queen's song bears some strong similiarities to Mother Brain's song in Super Metroid.
 * The Parasite Queen song was remixed for the Amorbis battle in Metroid Prime 2: Echoes and the Arctic Spawn and Fire Spawn in Metroid Prime Hunters.

Super Smash Bros. Brawl Trophy
"Space Pirates performed many experiments using Phazon as a means to artificially enhance physical strength. The Parasite Queen is the result of these experiments on one small life-form. This Parasite Queen lived in a nuclear power reactor and fired destructive beams at Samus from her mouth. The barrier that spun around the queen reflected her and Samus's attacks."

Metroid Prime, 2002