Altair IV is a fictional planet featured in the 1956 science fiction film Forbidden Planet. It is known for its lush landscapes and advanced technology, which is remnants of the extinct Krell civilization that once inhabited the planet. The planet's environment is both beautiful and dangerous, with mysterious creatures and phenomena. The story revolves around a space expedition sent to investigate the fate of a previous mission. The crew encounters Dr. Edward Morbius, the last human resident, who reveals the secrets of the planet and the powerful technology left behind by the Krell. The film explores themes of intelligence, power, and the consequences of technological advancement.