Hetocumtek was an alien who posed as a Native American god.
History
Early history
In the days of the Native Americans, Hetocumtek arrived on Earth and set himself up as a god infamous for his cruel and destructive nature. Eventually, a group of "medicine men" tricked the alien into a totem pole, trapping him. The totem pole was buried in the Nevada desert for fear of Hetocumtek's threats that he would break free when the totem pole "fell into the hands of men again". (TV: The Curse of Clyde Langer)
The curse of Clyde Langer
The totem pole was eventually discovered by archaeologists and taken to London to be displayed in a local museum. By then Hetocumtek had gone dormant, but residual energy in the totem pole caused a storm of fish to fall from the sky, drawing Sarah Jane Smith and her friends to the museum. During the investigation, Clyde Langer touched the totem pole and got a splinter, but thought nothing of it. This action fulfilled the requirements for Hetocumtek to escape. The alien knew Clyde had the power to destroy him while he was in the state of transition between his prison and freedom. That night he cursed Clyde's name, turning his friends and family against him and causing him to end up living on the streets.
Hetocumtek trapped within the totem pole. (TV: The Curse of Clyde Langer)
Only Sky and Mr Smith were immune to the alien's power, and Sky tried to ask the infected why they had turned on their friend but only got hateful responses. Meanwhile, Hetocumtek continued to pull himself free of the totem pole, its carved faces becoming organic and alive. Sky realised there was something wrong with Clyde's name itself. Confronting Sarah Jane and Rani Chandra with Mr Smith's backing, she got them to realise they had been brainwashed by an alien force and helped them break the conditioning by getting them to say Clyde's name. The group set off to find Clyde, then used Mr Smith to transport the totem pole to Sarah Jane's attic, where Hetocumtek almost completely freed himself. An angry Clyde confronted the alien; he touched the pole, destroying the alien and ending his threat for good. (TV: The Curse of Clyde Langer)
Abilities
Hetocumtek had a vast array of abilities, including weather manipulation; he could create fierce lightning storms by sheer will. His most prominent ability was a form of telepathy and brainwashing that he used to "curse" Clyde Langer's name to isolate him. This power caused anyone who said Clyde's name to feel an intense, unexplained hatred for him and drive him away. After that, the victim of the conditioning would feel an intense sadness, feeling they had lost something important but being unable to recall what. Getting the victim of the conditioning to say the cursed name themselves broke its effect. Only humans were susceptible to this power — although it included even genetically engineered humans like Luke Smith — as aliens like Mr Smith and Sky were immune. (TV: The Curse of Clyde Langer)
Appearance
Hetocumtek possessed orange-slitted eyes like a cat and an angular, grey face with an extendable jaw.