The Javan rhinoceros (Rhinoceros sondaicus) is the rarest of the five remaining rhinoceros species, and is critically endangered. It is estimated that there are only around 75 Javan rhinos left in the wild, all of which live in Ujung Kulon National Park on the island of Java in Indonesia.

Javan rhinos are smaller than Indian rhinoceroses, and are close in size to black rhinoceroses. They are the largest animal in Java and the second-largest animal in Indonesia after the Asian elephant. Javan rhinos have a single horn, which is only present on males. Their skin is dusky grey in color and has a number of loose folds, giving the appearance of armor plating.

Javan rhinos are solitary animals, except for mothers and calves. They are browsers and their diet consists mainly of leaves, fruits, and shoots. Javan rhinos play an important role in their ecosystem by dispersing seeds and helping to maintain the balance of plant life.

Javan rhinos are threatened by a number of factors, including poaching, habitat loss, and disease. Poaching is the biggest threat to Javan rhinos, as their horns are highly prized in traditional medicine. Habitat loss is also a major threat, as Javan rhinos have lost most of their historical range due to deforestation and agricultural development. Javan rhinos are also susceptible to a number of diseases, including foot-and-mouth disease and African swine fever.

Conservation efforts are underway to protect Javan rhinos, including anti-poaching patrols, habitat restoration, and captive breeding programs. However, more needs to be done to ensure the survival of this iconic species.