Ultra Series
Ultraman is a Seijin from the Land of Light M-78. Many Ultramen are usually red and silver (although several different colored ultra's have been seen in recent years, most of them are blue colored) and have glowing yellow eyes (except for red warriors) and they have many abilities, most of them are to fire energy beams from many positions of crossed hands. The Ultra beings’ main weakness is that they can only stay on Earth in giant form for a small time, usually not longer than three minutes, because of the small amount of energy supply (Earth's atmosphere decreases the solar energy). This is marked by a blue light on the character's body usually called the Color Timer (but Ultraseven, 21, Nexus Anphans, and Next did not have a color timer) or "warning light," which begins to blink red with increase in blinking as his energy supply goes down (and turns from grey to red) but Red warriors like Ultraseven had an orb on his head instead of a Color Timer. During this time the Ultra beings must either find a way to recharge or finish the fight as soon as possible, or forced to turn to human form, or worse, certain death. Sometimes some Ultra Warriors take them back to their home planet or when reflected sun rays by the mirrors on his color timer might charge them up. Some say another reason for Ultraman to recharge is because the Earth is badly polluted by humans, so Ultraman only has three minutes on Earth, but can survive long enough in outer space. The time limit only happens inside the Earth's atmosphere but they have none of those problems in outer space. In this case, Ultramen are almost always merged with a human host or create a human form for themselves in order to survive on Earth, more often than not reviving a recently dead person with their own lifeforce (Hikari did not revive the dead person but he controlled him). Ultra beings' also appear to be nearly immpossible to be permanently killed, as several times an Ultra being has been killed only to be revived by another member of their species. In other cases a large enough amount of energy can be provided to bring them back to life, usually provided by their human allies, even after being completely destroyed, as was the case with Mebius, death at the hands of Empera Seijin, only to be revived shortly thereafter by the life energy of his allies.