Interstellar invasion

An interstellar invasion is the introduction of one species or culture to a world in another star system inhabited by another species or culture and typically has a malignant effect on the local population.

Types of invasion

 * A hostile invasion is a wartime event where one sentient population attacks another population at their own homeworld, often with the intent of occupying local territories.
 * A habitat invasion, also called malignant colonization, is a natural occurrence where one species, regardless of sentience, is transported to another world and establishes itself as a dominant part of the local ecosystem and begins to steal resources from that environment's original inhabitants. An invasive population may be transported to their destination intentionally (such as livestock transported by colonists and merchants) or unintentionally (such as pests unknowingly hidden away aboard merchant ships).
 * A parasitic invasion is when a sentient or nonsentient species is transported to a world with the sole intent of completely draining its resources at the expense of the local population. Parasitic invasions may be classified as either a hostile or habitat invasion depending on the politics and violence related to the invasion.