The lion (Panthera leo) is a species (Si apre in una nuova finestra) in the family Felidae (Si apre in una nuova finestra) and a member of the genus (Si apre in una nuova finestra) Panthera (Si apre in una nuova finestra). It has a muscular, deep-chested body, short, rounded head, round ears, and a hairy tuft at the end of its tail. It is sexually dimorphic (Si apre in una nuova finestra); adult male lions have a prominent mane. With a typical head-to-body length of 184–208 cm (72–82 in) they are larger than females at 160–184 cm (63–72 in). It is a social species (Si apre in una nuova finestra), forming groups called prides. A lion pride consists of a few adult males, related females and cubs. Groups of female lions usually hunt together, preying mostly on large ungulates (Si apre in una nuova finestra). The lion is an apex (Si apre in una nuova finestra) and keystone predator (Si apre in una nuova finestra); although some lions scavenge when opportunities occur and have been known to hunt humans, the species typically does not.

Typically, the lion inhabits grasslands (Si apre in una nuova finestra) and savannas (Si apre in una nuova finestra), but is absent in dense forests (Si apre in una nuova finestra). It is usually more diurnal (Si apre in una nuova finestra) than other big cats, but when persecuted it adapts to being active at night (Si apre in una nuova finestra) and at twilight (Si apre in una nuova finestra). During the Neolithic (Si apre in una nuova finestra) period, the lion ranged throughout Africa (Si apre in una nuova finestra), Southeast Europe (Si apre in una nuova finestra), and Western (Si apre in una nuova finestra) and South Asia (Si apre in una nuova finestra)but today it has been reduced to fragmented populations in sub-Saharan Africa (Si apre in una nuova finestra) and one critically endangered population in western India. It has been listed as Vulnerable (Si apre in una nuova finestra) on the IUCN Red List (Si apre in una nuova finestra) since 1996 because populations in African countries have declined by about 43% since the early 1990s. Lion populations are untenable outside designated protected areas. Although the cause of the decline is not fully understood, habitat loss (Si apre in una nuova finestra) and conflicts with humans are the greatest causes for concern.

One of the most widely recognised animal symbols in human culture, the lion has been extensively depicted in sculptures and paintings, on national flags, and in contemporary films and literature. Lions have been kept in menageries (Si apre in una nuova finestra) since the time of the Roman Empire (Si apre in una nuova finestra) and have been a key species sought for exhibition in zoological gardens (Si apre in una nuova finestra) across the world since the late 18th century. Cultural depictions of lions (Si apre in una nuova finestra) were prominent in Ancient Egypt (Si apre in una nuova finestra), and depictions have occurred in virtually all ancient and medieval cultures in the lion's former and current ranges.