Largest Animal
Blue whales are the largest animals of all time. Females grow to a length of 79 to 89 feet, weighing well over 100 tons. The heaviest blue whale ever weighed was more than 190 tons, and the longest ever measured was more than 108 feet long.

Largest Animal (land)
African elephants are the heaviest and second tallest land animals. Large bulls (males) weigh more than 13,000 pounds and are 12 feet tall all the shoulder. Giraffes, which can grow to a height of 18 feet, are the tallest land animals. Large males weigh more than 4,000 pounds.

Largest Invertebrate
Giant squid, reaching lengths of 43 feet, are the largest invertebrates. They also have the largest eyes (about the size of a human head). The largest giant squid ever measured was 59 feet long.

Largest Invertebrate (land)
The coconut crab has a legspan of up to two and a half feet and weighs about 6.6 pounds. Native to tropical Indo-Pacific islands, this hermit crab species has muscular claws capable of punching holes into coconuts so that it can scoop out the flesh.

http://nationalzoo.si.edu/Animals/AnimalRecords/

The largest living single organism known on the planet is the fungus Armillaria ostoyae. more commonly known as the "honey mushroom" because of the golden-colored mushrooms it send up from its vast underground network in the autumn.

A mushroom of this type in the Malheur National Forest in the Strawberry Mountains of eastern Oregon, U.S. was found to be the largest fungal colony in the world, spanning 8.9 km² (2,200 acres) of area.

for more info follow the links below

Extreme Science - Largest organism

Wikipedia - Armillaria ostoyae

BBC report on largest fungus in the world

Humougous Fungus - ABC news