Its colourful golden crest feathers, as well as being called the "king of the birds" in European folklore, gives rise to its English and scientific names.

It superficially resembles the common firecrest (Regulus ignicapilla), which largely shares its European range, but the latter's bronze shoulders and strong face pattern are distinctive.

It may be killed by birds of prey or carry parasites, but its large range and population mean that it is not considered to present any significant conservation concerns.

It is similar in appearance to a warbler, with olive-green upper-parts, buff-white underparts, two white wing bars, and a plain face with conspicuous black irises.

Apart from the crest colour, the sexes are alike, although in fresh plumage, the female may have very slightly paler upper-parts and greyer underparts than the adult male.

[3] The goldcrest is usually easily distinguished from other small birds in its range, but poor views could possibly lead to confusion with the common firecrest or yellow-browed warbler.

The song of the male goldcrest is a very high, thin double note cedar, repeated 5–7 times and ending in a flourish, cedarcedar-cedar-cedar-cedar-stichi-see-pee.

[8] The song variations have been used to investigate the colonisation pattern of the Macaronesian islands by goldcrests, and identified a previously unknown subspecies.

[6] At the genetic level, the two Central Asian forms, R. r. sikkimensis and R. r. himalayensis, are very close to each other, and have differentiated only in the recent past, but they diverged from the western subspecies around 2.8 mya.

[9] Birds from the Canary Islands are particularly distinctive having a black forehead, pink-buff underparts and a darker closed wing,[2] and have been sometimes treated either as a subspecies of the common firecrest or as a different Regulus species altogether.

[25] Differences in songs, genetics and morphology suggests that the Azores were colonised in a single invasion in the late Pleistocene, about 100,000 years ago.

It is common in middle and northern temperate and boreal latitudes of Europe, between the 13–24 °C (55–75 °F) July isotherms, and thus predominantly in cooler climates than the firecrest.

[30] In Hungary, goldcrests stopping temporarily on migration were mostly found in scrub, including blackthorn, hawthorn and pear, which provided some protection from sparrowhawks.

This brings forward the northward migration of those bird species (including the goldcrest) that winter mainly within western or southern Europe.

A general climatic change resulting in more frequent positive North Atlantic oscillation events has led to earlier spring migration of these short-distance migrants since the 1980s.

[3] The nest is larger, shallower and less compact than that of the firecrest, with an internal diameter of about 9.0 cm (3.5 in),[38] and is constructed by both sexes, although the female does most of the work.

She leaves the nest more with increasing air temperature, and incubates more tightly when the light intensity is lower early and late in the day.

Even in aviary studies in which a female goldcrest was given an artificial eyestripe to facilitate mating with a male firecrest, the chicks were never raised by the mixed pair, and appeared to be poorly adapted compared to the parent species.

This is in contrast to the common firecrest, which mainly exploits the upper surface of branches in coniferous habitat and of leaves in deciduous trees.

In winter, flocks of goldcrests cover a given distance at only one-third of the speed of common firecrests, taking the smallest prey items ignored by their relative.

[47] The goldcrest has much the same range and habitat preference as the common chiffchaff, and there is some evidence that high breeding densities of the kinglet depress the population of the warbler, although the converse is not true.

[48] Nevertheless, there is no conclusive evidence that the decline of the chiffchaff subspecies Phylloscopus collybita abietinus in parts of Finland is due to competition with the willow warbler and goldcrest.

[6] This kinglet, like other species that prefer mixed-species foraging flocks in winter, hunts over a greater range of heights and vegetation types than when feeding alone.

[5] Several small passerine species survive freezing winter nights by inducing a lower metabolic rate and hypothermia, of a maximum of 10 °C (18 °F) below normal body temperature, in order to reduce energy consumption overnight.

[53] During an 18‑hour winter night, with temperatures as low as −25 °C (−13 °F) in the north of its range, goldcrests huddled together can each burn off fat equivalent to 20% of body weight to keep warm.

[54] Those with a relatively large amount of fat, may make stops during migration of only 1–2 days; although they have lost weight since commencing their journey, they have enough energy reserves to reach the wintering areas.

[5] Even in somewhat milder regions, where over-wintering is normal, exceptionally cold winters can cause such heavy losses that breeding populations take several years to recover.

[69] Aristotle (384–322 BC) and Pliny (23–79 AD) both wrote about the legend of a contest among the birds to see who should be their king, the title to be awarded to the one that could fly highest.

[32][73] The confusion was probably compounded by the similarity and consequent interchangeability of the Greek words for the wren (βασιλεύς basileus, "king") and the crests (βασιλισκος basiliskos, "kinglet").

There are unfounded legends that the goldcrest would hitch a ride in the feathers of the larger bird,[32] and similar stories claimed that owls provided the transport.