The Eurasian skylark (Alauda arvensis) is a passerine bird in the lark family, Alaudidae. It is a widespread species found across Europe and the Palearctic with introduced populations in Australia, New Zealand and on the Hawaiian Islands. It is a bird of open farmland and heath, known for the song of the male, which is delivered in hovering flight from heights of 50 to 100 metres (160 to 330 ft). The sexes are alike. It is streaked greyish-brown above and on the breast and has a buff-white belly.

The female Eurasian skylark builds an open nest in a shallow depression on open ground well away from trees, bushes and hedges. She lays three to five eggs which she incubates for around 11 days. The chicks are fed by both parents but leave the nest after eight to ten days, well before they can fly. They scatter and hide in the vegetation but continue to be fed by the parents until they can fly at 18 to 20 days of age. Nests are subject to high predation rates by larger birds and small mammals. The parents can have several broods in a single season.

The Eurasian skylark was described by the Swedish naturalist Carl Linnaeus in 1758 in the tenth edition of his Systema Naturae and retains its original binomial name of Alauda arvensis. It is one of the four species placed in the genus Alauda. The genus name is from the Latin alauda, "lark". Pliny thought the word was originally of Celtic origin. The specific arvensis is also Latin, and means "of the field". The results of a molecular phylogenetic study of the lark family Alaudidae published in 2013 suggested that Eurasian skylark is most closely related to the Oriental skylark Alauda gulgula.

Formerly, many authorities considered the Japanese skylark as a separate species. It is now usually considered a subspecies of the Eurasian skylark. Alternate names for the Eurasian skylark include northern skylark and sky lark.

Eleven subspecies are recognized:

Some authorities recognise the subspecies A. a. scotia Tschusi, 1903 and A. a. guillelmi Witherby, 1921. In the above list scotia is included in the nominate subspecies A. a. arvensis and guillelmi is included in A. a. sierrae.

The Eurasian skylark is 18–19 cm (7.1–7.5 in) in length. Like most other larks, the Eurasian skylark is a rather dull-looking species, being mainly brown above and paler below. It has a short blunt crest on the head, which can be raised and lowered. In flight it shows a short tail and short broad wings. The tail and the rear edge of the wings are edged with white, which are visible when the bird is flying away, but not if it is heading towards the observer. The male has broader wings than the female. This adaptation for more efficient hovering flight may have evolved because of female Eurasian skylarks' preference for males that sing and hover for longer periods and so demonstrate that they are likely to have good overall fitness.

It is known for the song of the male, which is delivered in hovering flight from heights of 50 to 100 m, when the singing bird may appear as just a dot in the sky from the ground. The long, unbroken song is a clear, bubbling warble delivered high in the air while the bird is rising, circling or hovering. The song generally lasts two to three minutes, but it tends to last longer later in the mating season, when songs can last for 20 minutes or more. At wind farm sites, male skylarks have been found to sing at higher frequencies as a result of wind turbine noise.