Suicide is usually viewed as maladaptive, a sign of severe emotional problems. But is there a possibility that it could be evolutionarily advantageous, at least in some situations?

• Wikipedia:
  An evolutionary explanation for suicide is that it may improve inclusive fitness. This may occur if the person committing suicide cannot have more children and takes resources away from relatives by staying alive. An objection is that deaths by healthy adolescents likely does not increase inclusive fitness. Adaptation to a very different ancestral environment may be maladaptive in the current one.
• Scientific American:
  People are most likely to commit suicide when their direct reproductive prospects are discouraging and, simultaneously, their continued existence is perceived, whether correctly or incorrectly, as reducing inclusive fitness by interfering with their genetic kin’s reproduction.

In animals:

• animal suicide
• self harm in animals