The Killer Whale is the most widespread and one of the most recognized mammals in the world. It is found in all the oceans from the Arctic to Antarctic, and tropical seas and open oceans. However, it is most often encountered in nearshore biologically rich areas and it occasionally enters estuaries and small bays. The Killer Whale has distinctive black and white markings with a prominent dorsal fin. The dorsal fin is from 1.0 to 1.8 meters tall in adult males and less than 0.7 meters in adult females. The head is rounded with a slight beak. Males can reach as long as 9.75 meters and females reach 8.53 meters.

Killer Whales usually travel in small groups known as pods. The average pod size for resident whales (see definition below) is about 12 individuals but up to 59 whales has been recorded. Transient pods range from one to four individuals. Single individuals, usually males, are occasionally encountered. The social group is matrilineal consisting of whales from two to three generations. Membership in the pod is stable although individuals will switch pods on occasion. Non-breeding females and males care and teach hunting methods to older calves of females with young calves. 

Breaching is the term that refers to the leaping out of the water to fall on the side with a big splash. Spyhopping is the vertical emergence of the whales head and part of its torso from the water. Tail lobbing occurs when a whale turns on to its belly and slaps the water surface with the top of its tail flukes while swimming upside down. Flipper slapping occurs when a whale turns on to its side and slaps the surface water with its fin. Killer Whales can dive for up to 17 minutes to a depth of at least 260 meters.

In the Pacific Northwest, resident Killer Whales are often referred to as belonging to southern, northern and offshore groups. The southern resident community is found generally around southern Vancouver Island and in Puget Sound. The northern resident community is found from northern Vancouver Island to southeast Alaska. The offshore community appears to inhabit the continental shelf break along the entire northwest coast, although information is scant.