Berserker Lord

Berserker Lord is a boss in Metroid Prime 3: Corruption. It is the first boss that Samus Aran faces in the game, and again on Elysia. The species are very similar to the Elite Pirate and Ingsmasher as they are a tougher version of a smaller, weaker, and more common variety.

A Berserker Lord is a Berserker Knight that has been corrupted with more Phazon than usual Knights can survive (Similar to the Omega Pirate compared to Elite Pirates).

When Samus battles it, she must first fire at two large, red circles on his shoulders. Once they are destroyed, he will fire projectiles at her which Samus must shoot at. This will cause them to fly back to Berserker Lord. Once a few of these projectiles have hit the creature, it will shoot a stream of a liquid-like substance, which is likely Phazon. The phazite plating on its head will then be destroyed, which Samus now must rapidly fire her Power Beam at while the Berserker Lord tries to pummel her with punches and shockwaves. Eventually, he will stumble into an electrical fence and fall into space, being hit by a passing ship. The fighter ship appears to be a Federation Stiletto Fighter, though it is only seen for a moment.

Later in the game on Elysia when Samus attempts to get the first Bomb Part a Berserker Lord reappears, damaged and dark in color. This may suggest that it is the initial boss, which survived the electrocution and collision. While not implicitly stated in the game, the official guide for the game states that "The Berserker Lord is the same boss you faced back on the Olympus."

In one of the preview trailers for Metroid Prime 3: Corruption, a PED Federation Soldier in Hyper mode is seen killing a Berserker Lord with ease. This footage is nowhere to be seen in the final version of the game.

It is likely that the Berserker Lords and the lesser Berserker Knights are the results of continued Phazon research on Elite Pirates, making them somewhat their descendants.

Logbook entry
Metroid Prime 3: Corruption: "Berserker Lords are highly resistant to damage. Their shoulders are the only unprotected area vulnerable to standard weapon fire. Their main defense lies in their head-mounted Phazite plating, which can only be destroyed by the projectiles it fires. Beserker Lords are a desperate measure, designed to exploit Phazon as much as possible. The few Berserker Knights that survive the highest level of corruption are promoted to Lord status. Lords are distinguished by their ornate Phazite plating and the Phazon reserves they carry on their backs."

Trivia

 * The Berserker Lord's battle music is a remix of the music heard when battling Arachnus-X from Metroid Fusion.
 * They have a large Phazite pod on their back as well as two smaller crystals within their claws.
 * Concept art refers to this creature as a "Phazon Berzerker Pirate."