The bearded reedling (Panurus biarmicus) is a small, long-tailed passerine bird found in reed beds near water in the temperate zone of Eurasia. It is frequently known as the bearded tit or bearded parrotbill, as it historically was believed to be closely related to tits or parrotbills. Today it is known to lack close relatives and it is the only species in the family Panuridae.

Bearded reedlings are strongly sexually dimorphic and form life-long pairs. They are highly productive and can breed several times in a season. They mainly feed on small invertebrates in summer and plant seeds in winter.

The bearded reedling was scientifically described in 1758 by the Swedish naturalist Carl Linnaeus in his 10th edition of Systema Naturae. He placed it with the tits in the genus Parus and coined the binomial name Parus biarmicus. Linnaeus based his entry on the "beardmanica or bearded tit-mouse" that had been described and illustrated in 1731 by the English naturalist Eleazar Albin and the "least butcher-bird" that had been described and illustrated in 1747 by George Edwards.

The bearded reedling was later moved from the tit family and placed with the parrotbills in the family Paradoxornithidae. Subsequent authors variously classified the species as a member of Muscicapidae (Old World flycatchers), Sylviidae (typical warblers) or Timaliidae (Old World babbler). Molecular phylogenetic studies show that it is a unique passerine, not part of any of these families. The bearded reedling is now placed in the monotypic family Panuridae that was introduced in 1860 (as the subfamily Panurinae) by Marc Athanase Parfait Œillet Des Murs. It lacks close relatives, but it is a sylvioid and nearest to the lark family Alaudidae. Panuridae and Alaudidae split from each other in the Early Miocene.

The current genus name, Panurus, was introduced by Carl Ludwig Koch in 1816. It is from Ancient Greek panu, "exceedingly", and ουρά, "tail". The specific biarmicus is from "Biarmia", a Latinised form of Bjarmaland, today part of Russia's Arkhangelsk Oblast and Kola Peninsula (a result of confusion when the species was first described; the bearded reedling does not range into these areas).

Three subspecies are generally recognised:

In some parts of central and eastern Europe, it is not entirely certain if P. b. biarmicus, P. b. russicus or intermediates are present. The three subspecies are quite similar; some authorities have suggested that the species should be considered monotypic (i.e. no distinct subspecies) because of the amount of individual variation and overall cline in the variation.

The bearded reedling is native to temperate Europe and Asia, ranging from Spain, France and the British Isles to the Manchurian region, but its distribution tends to be quite spotty because of its habitat preference. Maps often show most of its Asian range as a single large continuous section (instead of more spotty), but this is due to limited details in monitoring data from this area relative to the western part of its range. In Europe, it used to be limited to mid and low latitudes, also including Great Britain, but in the second half of the 20th century it has expanded north into Scandinavia, Finland and the northern Baltics.