The Proboscis Monkey (Nasalis larvatus):

Blessed with its unmistakable facial feature, this is one of the world's ugliest, yet most fascinating, monkeys.  In Sabah, it is also known as "monyet belanda" or "Dutchman monkey", a lighthearted and slightly irreverent reminder of Borneo's colonial days.

The proboscis monkey is found only in Borneo but it is threaten - studies estimate that there may only be about 7000 left in the world, of which about 1,000 are in Sabah..

Best place to see: Sukau / Kinabatangan Area (nearly guaranteed) and Klias Wetlands (more elusive than in Sukau)

The Sumatran Rhinoceros (Dicerorhinus sumatrensis):

General coloration usually dark brow, but appearance may vary after bathing  in water or mud.  Hairy especially when young, but the hair is often not apparent in the field.  When disturbed unexpectedly, this rhinoceros usually flees rapidly, sometimes giving a series of short, hoarse barks. They are mainly active from late afternoon to mid morning and rest during the hot hours of the day in a mud wallow, shaded spot or ridge top. Feeds on mature leaves and twigs.

Best place to see (with LOTS of luck): Tabin Wildlife Conservation Area, Danum Valley; Sepilok Orang Utan Rehabilitation Centre

Pygmy Elephants (Elephas maxima sp):

Mostly active from about two hours before dusk until two hours after dawn.  Diet consists mainly of monocotyledonous plants, including soft grasses, the growing part parts of palms and banana stems. Group usually contains between three to forty individuals. The population of Sabah is estimated at 500-1100.

Only recently DNA tests have reviled that Sabah's elephants are not 'Asian Elephants', but a subspecies that evolved in Borneo over the past 100'000-200'000 years. They are smaller, tamer and milder tempered compared with other Asian elephants.
 

Best place to see (with luck): Sukau/Kinabatangan Area, Tabin Wildlife Conservation Area, Danum Valley; Sepilok Orang Utan Rehabilitation Centre

Orang Utan (Pongo pygmaeus):

Coloration generally reddish-brown, varying from orange to dark reddish-brown in old individuals. Often detected by its nests - a rough array of bent and broken twigs and small branches partially woven together. No other primates make nests. They can be sometimes detected by footprints on bare soil and discarded food that they chew. Diet mainly fruits and young leaves, occasionally insects. Usually solitary, but young remain with mother until 5 or 6 years of age. In 1997 WWF Report estimated that less than 30,000 orang-utans are left in the world, but the numbers have fallen further following devastation of forest fires in 1998 and ongoing, rapid land development schemes for oil palm plantations.

Best place to see: Sepilok Orang Utan Rehabilitation Centre; Sukau/Kinabatangan Area (though in the wild they are very difficult to spot), Danum Valley

The Oriental Darter (Anhinga melanogaster):

The Oriental Darter, also known as the snake-bird, has totally disappeared from the wetlands of Peninsular Malaysia but it is found here in great numbers.  Parts of this area is believed to be an important breeding ground for this species and essential to its survival. Many other rare water birds, including those that have disappeared from other parts of Malaysia and neighbouring countires, are found here.

Best place to see: Sukau / Kinabatangan