An alien from the 17th planet, Planet Icarus, that came to conquer the Earth and planned to build its forward base in the 4th dimension. Alien Icarus can use its teleportation abilities at will and attacks enemies using its Arrow Beam.

Alien Icarus set up base in a residential area where it disguised itself in human form. In the following two months it perfected a 4th dimension control device which linked the 3rd and 4th dimensions together. Dan discovered the existence of dimensional rifts caused by the device and Alien Icarus allowed him to follow it into the 4th dimension. With Dan trapped in the 4th dimension and unable to transform into Ultraseven, Alien Icarus began its plan to attack the Earth with its spaceship. Alien Icarus used its control device to move freely between the 3rd and 4th dimensions and launched several attacks on Tokyo.

However, after Dan destroyed the control device and made his way back to the 3rd dimension. He transformed into Ultraseven and Alien Icarus changed into its true giant form as the fight began. Alien Icarus was greatly injured by Ultraseven’s eye slugger and then defeated after being thrown by his Ultra Psychokinesis.