The Observers are an alien race who claim to be hyper-intelligent. They have highly-developed mental abilities, and all share the name "Observer". The race also claims to be without bodies (despite obvious evidence to the contrary) and carry their bright-blue brains in large bowls, rather than inside their (supposedly nonexistent) skulls.
They all claim to be omniscient and omnipotent, but they frequently fail to demonstrate these supposed abilities. In one of their earlier appearances, The Observers administer a series of tests to Pearl Forrester, Bobo, and the residents of Satellite of Love to see if any of them are deserving to become one of their kind. The Observer that later came to be known as Brain Guy is surprised when Tom Servo scores higher than he had, which leads to Brain Guy being painfully punished.
In time, the survivors are able to reconstitute their planet (as stated in Experiment 904 The Deadly Bees). Observers 1 & 2 tracked Brain Guy through time and space to Castle Forrester, where they attempt to take him back to their planet and blow up the Earth as they left. Brain Guy initially agrees, but later changes his mind and (with the help of Pearl and Bobo) separates his former comrades from their brains. He then changes them into Wisconsinites and sends them off to a life of cheering for the Green Bay Packers.
A group of Observers (not including the two that Brain Guy banished) attends Kinga Forrester's wedding to Jonah Heston (which is disrupted by Jonah's apparent death at the hands of Max and Reptilicus Metallicus).