Beta Lyrae (β Lyrae, abbreviated Beta Lyr, β Lyr) officially named Sheliak (Arabic: الشلياق, Romanization: ash-Shiliyāq) (IPA: /ˈʃiːliæk/), the traditional name of the system, is a multiple star system in the constellation of Lyra. Based on parallax measurements obtained during the Hipparcos mission, it is approximately 960 light-years (290 parsecs) distant from the Sun.

Although it appears as a single point of light to the naked eye, it actually consists of six components of apparent magnitude 14.3 or brighter. The brightest component, designated Beta Lyrae A, is itself a triple star system, consisting of an eclipsing binary pair (Aa) and a single star (Ab). The binary pair's two components are designated Beta Lyrae Aa1 and Aa2. The additional five components, designated Beta Lyrae B, C, D, E, and F, are currently considered to be single stars.

β Lyrae (Latinised to Beta Lyrae) is the system's Bayer designation, established by Johann Bayer in his Uranometria of 1603, and denotes that it is the second brightest star in the Lyra constellation. WDS J18501+3322 is a designation in the Washington Double Star Catalog. The designations of the constituents as Beta Lyrae A, B and C, or alternatively WDS J18501+3322A, B and C, and additionally WDS J18501+3322D, E and F, and those of A's components - Aa1, Aa2 and Ab - derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).

Beta Lyrae bore the traditional name Sheliak (occasionally Shelyak or Shiliak), derived from the Arabic الشلياق šiliyāq or Al Shilyāk, one of the names of the constellation of Lyra in Islamic astronomy. Notably, in Arabic sources the Lyra constellation is primarily referred to as سِلْيَاق (Romanization: Siliyāq), whereas شلياق (Šiliyāq) primarily is used to refer to Beta Lyrae in what might be a form of linguistic reborrowing. Persian sources on the other hand, do refer to the Lyra constellation as شلياق (Šiliyāq), which may be the source of this confusion.

In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalogue and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems. It approved the name Sheliak for the component Beta Lyrae Aa1 on 21 August 2016 and it is now so included in the List of IAU-approved Star Names.

In Chinese astronomy, Tsan Tae (漸台 (Jiāntāi), meaning Clepsydra Terrace, refers to an asterism consisting of this star, Delta² Lyrae, Gamma Lyrae and Iota Lyrae. Consequently, the Chinese name for Beta Lyrae itself is 漸台二 (Jiāntāièr, English: the Second Star of Clepsydra Terrace.)

Beta Lyrae Aa is a semidetached binary system made up of a stellar class B6-8 primary star and a secondary that is probably also a B-type star. The fainter, less massive star in the system was once the more massive member of the pair, which caused it to evolve away from the main sequence first and become a giant star. Because the pair are in a close orbit, as this star expanded into a giant it filled its Roche lobe and transferred most of its mass over to its companion.

The secondary, now more massive star is surrounded by an accretion disk from this mass transfer, with bipolar, jet-like features projecting perpendicular to the disk. This accretion disk blocks humans' view of the secondary star, lowering its apparent luminosity and making it difficult for astronomers to pinpoint what its stellar type is. The amount of mass being transferred between the two stars is about 2 × 10⁻⁵ solar masses per year, or the equivalent of the Sun's mass every 50,000 years, which results in an increase in orbital period of about 19 seconds each year. The spectrum of Beta Lyrae shows emission lines produced by the accretion disc. The disc produces around 20% of the brightness of the system.