Wild boars can be very aggressive

[BTA]

Wild boars are real life monsters of legend. They are also very smart. They usually run first, hide, backtrack, conceal their tracks, have exceptional sense of smell, good hearing and poor eyesight. Herds are female, single boars are male, usually. During rutting season (November to January), males develop subcutaneous armor. They hunt small prey, eat almost everything, even plants poisonous to us.

A male, in rutting season, might attack without provocation. Females in a herd might defend their young if I stumbled into their midst.

[PALU]

Currently wild boars can be quite aggressive when you've injured them, with a behavior similar to that of badgers.

[Tom H]

I hunted down a wild sow. Was beginning to butcher it when another showed up and went kamikaze! Maybe it's supposed to be a boar but it was named a wild sow. Anyway, it was plenty belligerent.

[davidor]

sow is just a female boar

[Faurric]

I hunted down a wild sow. Was beginning to butcher it when another showed up and went kamikaze! Maybe it's supposed to be a boar but it was named a wild sow. Anyway, it was plenty belligerent.

I've had a number of encounters where when I killed one member of a herd, most ran, but one alpha type got aggressive. I've seen this in wolves, sows, and even reindeer.