The mistle thrush (Turdus viscivorus) is a bird common to much of Europe, temperate Asia and North Africa. It is a year-round resident in a large part of its range, but northern and eastern populations migrate south for the winter, often in small flocks. It is a large thrush with pale grey-brown upper parts, a greyish-white chin and throat, and black spots on its pale yellow and off-white under parts. The sexes are similar in plumage, and its three subspecies show only minimal differences. The male has a loud, far-carrying song which is delivered even in wet and windy weather, earning the bird the old name of stormcock. Historically, the name was also sometimes spelled "missel thrush".

Found in open woods, parks, hedges and cultivated land, the mistle thrush feeds on a wide variety of invertebrates, seeds and berries. Its preferred fruit include those of mistletoe, holly, rowan, and yew. Mistletoe is favoured where it is available, and this is reflected in the thrush's English and scientific names; the plant, a parasitic species, benefits from its seeds being excreted by the thrush onto branches where they can germinate. In winter, a mistle thrush will vigorously defend mistletoe clumps or other fruit-bearing trees as a food reserve for when times are hard, chasing off other thrushes and other fruit-eating birds like waxwings.

The open cup nest is built against a trunk or in a forked branch, and is fearlessly defended against potential predators, sometimes including humans or cats. The clutch, typically of three to five eggs, is incubated for 12–15 days, mainly by the female. The chicks fledge about 14–16 days after hatching. There are normally two broods. There was a range expansion in the 18th and early 19th centuries, and a small decline in recent decades, perhaps due to changes in agricultural practices. Given its numbers and large range, this thrush is classified by the International Union for Conservation of Nature as being of least concern.

The mistle thrush was first described by Carl Linnaeus in his 1758 10th edition of Systema Naturae under its current scientific name. Turdus is the Latin for "thrush", and viscivorus, "mistletoe eater", comes from viscum "mistletoe" and vorare, "to devour". The bird's liking for mistletoe berries is also indicated by its English name, "mistle" being an old name for the plant.

There are more than 60 species of medium to large thrushes in the genus Turdus, characterised by rounded heads, longish pointed wings, and usually melodious songs. A mitochondrial DNA study identified the mistle thrush's closest relatives as the similarly plumaged song and Chinese thrushes; these three species are early offshoots from the Eurasian lineage of Turdus thrushes after they spread north from Africa. They are less closely related to other European thrush species such as the blackbird (T. merula) which are descended from ancestors that had colonised the Canary Islands from Africa and subsequently reached Europe from there.

At least eight subspecies have been proposed, but the differences between them are mainly clinal, with birds being paler and less densely spotted in the east of the range. The accepted subspecies as of 2024 are:

There is some dispute as to the boundary between T. v. viscivorus and T. v. bonapartei; some cite birds from Siberia east of the Ob as being in T. v. bonapartei, while others restrict T. v. bonapartei to the populations further south in the mountains of central Asia, with the entire Siberian population in T. v. viscivorus. An isolated population in Crimea has sometimes been separated as T. v. tauricus, but this is not considered to be a valid form. Mistle thrush fossils have been found in Pleistocene deposits from Poland and Sicily.

The mistle thrush is the largest thrush native to Europe. The nominate subspecies measures 27–28 cm (11–11 in) in length, with a 45 cm (18 in) wingspan. It weighs 93 to 167 g (3.3 to 5.9 oz), with an average of around 130 g (4.6 oz). It has a stocky upright posture when on the ground. It has pale grey-brown upperparts, the chin and throat are greyish-white, and the yellowish-buff breast and off-white belly are marked with round black spots. The spotting becomes denser on the lower chest. The long tail has white tips on the outer feathers, and the underwing coverts are white. The eyes are dark brown and the bill is blackish with a yellowish base to the lower mandible. The legs and feet are yellowish-brown. There are no plumage differences between the sexes. Juveniles are similar to adults, but they have paler upperparts with creamy 'teardrop' centres to many of the feathers and smaller spots on the yellowish underparts. By their first winter they are very similar to adults, but the underparts are usually more buff-toned.