The industrious miners known as the Cragsters live in a vast network of tunnels and caverns dug deep underground.
- Krader - The tough, serious, no-nonsense leader with a huge drill hand.
- Seismo - The shy and quiet one with earthquake-causing feet.
- Shuff - The cute, clumsy, and helpful one who breaks everything with his wrecking-ball-like body.
Mixopolis Middle School students
- Rocky: A background Cragster.
- Boldurr: A bully Cragster.
- Their leader is Krader.
- They are based upon the element of earth.
- Seismo and Shuff hate Zorch due to his actions, but Krader doesn't seem to mind him.
- Their Max form only has four teeth.
- They are not very intelligent, for they can only speak simple words and have bad grammar (speaking in third person). However, they are very cunning.
- They invented Rockball as a sport for Mixels Land.
- Seismo is often mistaken as the leader.
- The name "Cragster" is a play on the word "craggy", which is defined as "rough and uneven", describing rocks.
- Their Cycloptic member is Seismo.
- Their Max is a troll-like rock creature.
- Krader is the only core Cragster who doesn't have the letter "S" at the beginning of his name.
- Shuff is the only core Cragster who doesn't have the letter "E" in his name.
- None of them have an opening mouth in LEGO form.
- The shortest member is Krader and the tallest is Seismo.