Mini-Kraid

Mini Kraid (also known as Fake Kraid or Kraid Spawn) is weaker and sometimes smaller version of Kraid seen in Metroid and Super Metroid.

Metroid
There are a few paths that lead to the actual Kraid, so the player may not even encounter fake Kraid. He is a brown and blue version of the regular Kraid, however the same size. He only takes one missile to kill and constantly respawns like a regular enemy once Samus leaves the room and re-enters.

Super Metroid
A few rooms before Kraid, Samus will encounter this smaller version of Kraid. Before she sees him, spikes will fly into her. As she progresses through the room, she will eventually come face to face to Mini Kraid.

Mini Kraid continually shoots spikes from its stomach and will occasionally spit some dirt from its mouth which will deal some damage. A few Missiles or one Super Missile will easily kill Mini Kraid. He will respawn once Samus re-enters the room.

Kraid in Metroid was originally around this size, leading players to believe they were fighting the real Kraid when Super Metroid was first released. However, upon defeating Mini Kraid, nothing happens, though one of the next rooms contains the much larger real Kraid.

It is possible that mini Kraid is in fact the infant offspring of Kraid.