The saltwater crocodile (Crocodylus porosus), also known as the estuarine or Indo-Pacific crocodile, is the largest of all living reptiles. It is found in suitable habitats from Northern Australia through Southeast Asia to the eastern coast of India.

The saltwater crocodile has a longer muzzle than the mugger crocodile; its length is twice its width at the base. The saltwater crocodile has fewer armor plates on its neck than other crocodilians, and its broad body contrasts with that of most other lean crocodiles, leading to early unverified assumptions the reptile was an alligator.

Newly hatched saltwater crocodiles measure about 25 to 30 centimetres (9.8–12 in) long and weigh an average of 70 grams (2.5 oz). Males reach sexual maturity at around 3.3 metres (11 ft) at around 16 years of age, while females reach sexual maturity at 2.1 metres (6.9 ft) and 12–14 years. An adult male saltwater crocodile's weight is 409 to 1,000 kilograms (900–2,200 lb) and length is normally 4.1 to 5.5 metres (13–18 ft). However, mature males can exceed 6 metres (20 ft) and weigh more than 1,000 kilograms (2,200 lb), and this species is the only extant crocodilian to regularly reach or exceed 4.8 metres (16 ft). Weight can vary enormously based upon the condition and age; older males tend to outweigh younger ones since they maintain prime territories with access to better, more abundant prey. For example, crocodiles at 4.8 metres (16 ft) long have ranged in mass variously from 522 kilograms (1,150 lb) to 1,000 kilograms (2,200 lb). This species has the greatest sexual dimorphism of any modern crocodilian, with the females being much smaller than males. Typical female body lengths range from 2.3 to 3.5 metres (8–11 ft). The largest female on record measured about 4.2 metres (14 ft). The mean weight of the species as a whole is roughly 450 kilograms (1,000 lb).