Queen Metroids are the Metroids that propagate the entire species and are also the last in the species' evolutionary line. They are less common than other Metroids due to them needing specific genes in order to mature into queens, as Samus remarks in Other M. In Metroid: Other M, the Galactic Federation researchers aboard Bottle Ship genetically manipulated genes from clones of the Metroid Hatchling, allowing at least one Metroid to grow to a Queen Metroid.
After wiping out the other Metroids while on her mission to exterminate the Metroids on SR388, Samus battles a Queen Metroid. This queen attacks by firing energy bursts, and it will also extend her neck to ram or bite Samus. In order to defeat it, Samus must fire Missiles directly at its face. If a missile is shot into its open mouth, the queen will become stunned allowing Samus to roll into her stomach and lay Bombs.
Later, Samus encounters another Queen Metroid on the Bottle Ship; this particular Queen Metroid was used by the Galactic Federation researchers as a control specimen for the cold-resistant Metroids. It is destroyed after Samus grapples into its mouth and detonates a Power Bomb in its stomach. This Queen is also responsible for the death of the Ridley clone.