The only characters to use Cerebro on a frequent basis are Professor X, Jean Grey, Emma Frost and the Stepford Cuckoos. However, Rachel Summers, Danielle Moonstar, Psylocke and Ruth Aldine have also used it. After the device was upgraded to Cerebra, Cassandra Nova used it in order to exchange minds with Xavier. The Stepford Cuckoos once utilized the machine to amplify their combined ability, with only one of them directly connected to the machine, but all of them experiencing its interaction due to their psychic rapport. The strain of mentally halting a riot during Open Day killed Sophie, the Stepford Cuckoo who was hooked up to Cerebra. Sophie was both inexperienced at using Cerebra and was high on the mutant-enhancing drug "Kick"; however, it was revealed that it was not the strain of using the machine, nor the drug, that was responsible for her death, but Sophie's own sister Esme, who also used Kick to power her own abilities, seize control of the Cuckoos temporarily, and manipulate Sophie into her death. The now remaining three Cuckoos demonstrated that they were capable of using Cerebra with relative ease in Phoenix: Endsong.