The Berserker Lord is a boss in Metroid Prime 3: Corruption. It is the first boss that Samus Aran faces in the game on the G.F.S. Olympus, and again on Elysia. The Lords are very similar to the Elite Pirate, playing the same role in terms of gameplay.
A Berserker Lord is a Berserker Knight that has survived further corruption with more Phazon than what Knights can usually tolerate (similar to the Omega Pirate compared to Elite Pirates).
When first encountered, while Samus is heading back to her gunship, a yell is heard and a man's body is flown out of a window. The Berserker Lord appears right after the dead body. Samus commands her gunship to fly into a safe spot while the two fight in an electric cage. After Samus defeats the Lord, he falls back into the electrical fence falling to the depths of space only to be crushed by a Space Pirate Fighter, killing them both.
The Lord appears unexpectedly in Elysia, most likely to prevent her from retrieving the Bomb Part. When defeated, it merely dissolves into ash and dust.