Baltan

The Baltans are microscopic creatures who escape their world when it was destroyed while they were doing some nuclear testings. Roughly 60,600,000,000 microscopic Baltans came to the planet Earth, originally because of engine trouble with their spacecraft. After searching for sufficient technical components to repair their engines at a science facility, they later decided to claim Earth as their own. When they landed on Earth, the single Baltan alien appeared to humans were either human size or gigantic size, this is actally large group of the Baltan united.

The Science Patrol tried to negotiate with the Baltans. Suggest Mars as an alternative home for the Baltans, but they claimed Mars was less than optimal. Shin Hayata, Ultraman's host, suggested that the Baltans could live on Earth in peace if they obeyed human laws but Baltans were not compromises (and that was before anybody learned of the Baltans' vast numbers).

Eventually Baltan going to wipe out life on Earth, but Ultraman destroyed giant Baltan and the spaceship with the Specium Ray. It turn out that Baltan is very weak against Specium substance, which also found on Mars.

Yet the threat of Baltan does not end, Ultraman himelf later encounter another Baltan (known as Baltan II). They attack Earth once again when the Science Patrol went into space to rescue the Ohtori spaceship.

His fellow Ultramen also fight these aliens.

Abilities
Baltan's claws are capable to release powerful energy missles or paralyze ray. It can can take over a human's mind and use one as translator. It also has flight ability and may project multiple illusion of itself to confuse enemy. By disassembling and rearrange, it look as if a Baltans can teleport over short distances.

Baltan II share mind control, growth and teleport ability with the first one. Instead of paralyze ray, it flash stun light from claws. It can generate gravity storm, increase or decrease garvity at wiil. To protect itself from Specium, it may open up its chest to reveal reflective mirrors that provide protection from energy attack. However, this does not work against Ultraman's Ultra Slash energy saw. Its other method of protection is energy shield.