The clouded leopard was previously considered a single species, but has recently been divided into two based on molecular (mitochondrial DNA, microsatellites and chromosomal) and morphological (pelage and craniodental) analyses. The mainland clouded leopard (Neofelis nebulosa) occurs in South-east Asia on the mainland, the Sunda clouded leopard 

(Neofelis diardi) only inhabits the islands Sumatra and Borneo. Before this division into two species, there were four subspecies of N. nebulosa described: Neofelis nebulosa diardi inhabiting Borneo, Sumatra and the Batu Islands (now N. diardi), N. n. macrosceloides occurring in Bhutan, Burma, India and Nepal, N. n. nebulosa recorded in Cambodia, China, Laos, Peninsular Malaysia, Thailand and Vietnam, and N. n. brachyura endemic to the island of Taiwan. The data currently available does not support the distinction of any subspecies of the Mainland clouded leopard and it is therefore considered as a monotypic species.

The clouded leopard is of intermediate size (comparable to a small leopard) with a tail nearly as long as the head and body, and relatively short legs. Males are larger than females. The clouded leopard has some very special characteristics: Its legs are short, stout and end in broad paws. The hind legs are much longer than the front ones and its tail is exceptionally long (typically equivalent to head-body length), plush and enables it to skilfully balance on thin tree branches. Its skull is quite long, and, together with its sister species the Sunda clouded leopard, its canine teeth are proportionally longer than those of any other extant cat. Also, the patterns of its coat with cloud-like rosettes with dark outlines and lighter centres on a light background are unique and gave the clouded leopard its name. The background colour of the coat can vary from yellowish brown, ochraceaous, tawny to silvery grey to earthy brown or dark grey. Two long stripes run along the spine and the tail has 6 crosswise stripes. The underside is white or pale tawny, its limbs and underbelly are marked with large black ovals and the back of its neck is conspicuously marked with two thick black bars.

The clouded leopard has body and behavioural characteristics which fall between the ones of the small and the large cat species. For example, it cannot roar and can only purr like small cat species but its feeding behaviour, grooming and its body postures are similar to those of large cat species.  

The clouded leopard is considered Vulnerable in the IUCN Red List. In the National Red List of Nepal, it is considered Endangered. There is little scientific information available on the clouded leopard in the wild. In some parts of its wide range, it may be common but very little is known about its population trends, since it inhabits typically very dense vegetation and is very elusive. Its habitat is generally fragmented.The estimated global population size is between 1,600–29,000 mature adults, although it is likely more towards the lower end of this estimate and between 3,700 and 5,580 mature individuals.

Clouded leopards are distributed from the eastern and southern Himalayan foothills in Nepal, through Bhutan and India to Myanmar, southern China, Peninsular Malaysia and throughout Indochina (Vietnam, Lao PDR, Thailand, Cambodia) and Peninsular Malaysia. High declines were detected in China, Myanmar and Vietnam. Its current status in China is poorly known. It had a wide distribution south of the Yangtze but there are very few recent records. It has also been reported as relatively common in the Chinese province Jiangxi and Anhui in the past. It has been recorded in central, western and southern Sichuan and in the Namcha Barwa region in Tibet. A rough population estimate for south-west China based on home range size estimations from Thailand, and on camera trapping, scat collection and sightings between 2005 and 2007 resulted in an estimate of 70 individuals in southern Yunnan.

The presence of the clouded leopard in Bangladesh is uncertain. It may still occur marginally in the country in mixed evergreen forests, but little of this forested habitat remains. The previously described subspecies of the clouded leopard occurring on the island of Taiwan, is thought to be extinct, with the last direct record of occurrence stemming from 1983, and the last record of a skin from 1989. Similarly, the species may be close to extinct in Vietnam. Here, they have not detected the species on camera trap studies since 2013. In India, it has been reported from the states Arunachal Pradesh, Assam, Bihar, Meghalaya, Mizoram, Nagaland, Sikkim, Tripura and northern parts of West Bengal. The clouded leopard occurred once throughout the countries in Indochina and Peninsular Malaysia but nowadays its range is largely restricted to forested and protected areas. It is found in approximately 36% of its historic range.

In Bhutan, mainland clouded leopards mostly occur in the forested southern areas rather than the northern areas due to the rapid increase in latitudinal elevation. Here, they occur both inside and outside protected areas. In Nepal, mainland clouded leopards occur relatively extensively in eastern Nepal between Terai (in the south) and the Nepal-Tibet (China) border (in the north), and occur up until the Annapurna Conservation Area in the west. In India, mainland clouded leopards widely occur in the northeast and as far west as Valmiki Tiger Reserve, they occur in relatively high densities as high as 4.7 and 5.1 individuals per 100 km² in Manas National Park and Dampa Tiger Reserve respectively. In Bangladesh, the species likely persists in suitable mountainous habitat in the south-eastern part of the country albeit in very small numbers. Despite the majority of Myanmar being deemed suitable habitat for the clouded leopard, the species likely is thinly but widely distributed across the evergreen forests in northern and southern Myanmar. The species has not been detected in seemingly suitable areas and only occurs in low numbers. In Lao PDR, clouded leopards have become very rare and likely have been extirpated from many forested areas. There have been no recent records from southern Lao PDR, if they do occur in this area, they likely are there in extremely low numbers. In China, there have been few recent records and the species’ current distribution largely seems restricted to areas in Yunan Province along the Lao PDR and Myanmar border, although not much is known about it. In Thailand, on the other hand, mainland clouded leopards seem to be widely distributed across the highly fragmented forests. There, however, is a lack of recent records in the relatively unexplored forests in the northern, northeastern and southern part of the country. In Cambodia, the species still occurs in protected areas in the Cardamom Rainforest Landscape and Virachey National. In other parts of Cambodia, however, they have become extremely rare and may even have been extirpated. In Viet Nam, there are no recent records and the species might have been extirpated. In Malaysia, the species is still relatively widespread and mostly occur within the Central Forest Spine map.

The difference in the estimated densities (0.6 and 3.1 / 100 km²) from two different parts of Htamanthi Wildlife Sanctuary, Myanmar, is thought to be due to the presence or absence of tigers in the respective areas.

The clouded leopard is solitary and mostly cathemeral (i.e. can be active at any time of day and night), but mostly with slightly higher amounts of activity at night or crepuscule. It is a remarkably secretive creature. The clouded leopard is a highly arboreal species which moves easily through trees. It is an excellent climber, one of the few cats which can also climb headfirst down a vertical trunk and hang from branches by their hind feet. The clouded leopard uses the trees to rest, but it likely also forages in them. Although the clouded leopard is such a good climber, it also can travel over quite long distances on the ground. In Thailand, male and female clouded leopards seem to have similar home range sizes between 30-40 km² with intensively used core areas of 3-5 km². Home ranges of females and males overlap substantially and also home ranges of males seem to have quite high overlap. It marks its territory with scent. The species may occur in higher densities when other larger cats, i.e. tigers and leopards, occur in lower densities.

The age at first reproduction is around 26 months for females and for males. Estrus lasts for approximately 6 days, the estrus cycle for 30 days and gestation for 87-99 days. Age at the last reproduction is 12 to 15 years. Data stems from studies on captive animals preceding the relatively recent split of N. nebulosa and N. diardi and cannot be distinguished between the two species. Post-split studies are not available.

The clouded leopard is included in CITES Appendix I and protected by national legislation across most of its range. Hunting is prohibited in Bangladesh, Cambodia, China, India, Malaysia, Myanmar, Nepal, Taiwan, Thailand, and Vietnam. Hunting is regulated in Laos but it has no legal protection outside protected areas in Bhutan. It occurs in many protected areas.

Proper measures are required to minimise threats such as designing and implementing regional management plans and strategies. Habitat destruction must be diminished as much as possible and law enforcement and protection against illegal hunting has to be improved for successful conservation of the clouded leopard. Raising awareness could become an important measure as well. In China, some environmental education of local school children and adults has taken place in order to improve public awareness of the species.

There is a need for more investigation and studies of the ecology, distribution and status of the clouded leopard. The increased use of camera traps has led to a better understanding of its distribution and recent research has improved the knowledge about its population status. However, there is still basic ecological information missing, the amount of information on its distribution and status is still not satisfying and more research is needed to enable taking appropriate conservation measures.  Since the species occurs in many protected areas, improving the effectiveness of the management of these areas through the implementation of the Zero-poaching tool kit (http://zeropoaching.org/) and achieving Conservation Assured Tiger Standards (CA|TS), should significantly reduce the threats faced by the mainland clouded leopards within these protected areas. As the species occurs in transboundary landscapes, it should be considered in transboundary conservation planning.

There is a need for more investigation and studies of the ecology, distribution and status of the clouded leopard. The increased use of camera traps has led to a better understanding of its distribution and recent research has improved the knowledge about its population status. However, there is still basic ecological information missing, the amount of information on its distribution and status is still not satisfying and more research is needed to enable taking appropriate conservation measures.