#1 The Blue Whale
The blue whale that can be up to 30 meters in length, 180 metric tons or more in weight and about the size of an average Asian Elephant is the largest known animal to have ever existed.
Image Credit: animalstown.com
#2 The Whale Shark
The whale shark which can be up to 14 meter (46 ft) long and 30 metric tons (66,000 lb) is known as a slow-moving and the largest extant fish species.
Image Credit: nationalgeographic.com