Danger

Dangers in Spore are things which are out to hinder your progress as an evolving creature or advancing race, and must be overcome or you risk anything from death to the collapse of your civilisation.

Tide pool phase
Enemies in the tide pool phase are generally micro-organisms (microbes) that are larger than the player's own microbe. From what has been seen of the tide pool phase, these seem to be, among other things, brown swarms that hurt the player's microbe when it gets too close. These microbes may or may not be pollinated content created by other players.

Creature phase
Other creatures in the creature phase may attack the player's creature either because the creature is a suitable food source, or because it is trespassing on their territory. Creatures will also attack your eggs until they hatch.

Tribal phase
In the Tribal phase, war parties from other tribes or dangerous creatures can attack your tribe.

Civilization phase
In the civ phase, other cities can send various types of vehicles to destroy your cities, or they can use more subtle methods, like cultural or economic domination.