Albireo (β Cyg / β Cygni / Beta Cygni) is the third brightest star in the constellation Cygnus. Although it has the Bayer designation "beta", it is actually fainter than Gamma Cygni.

Since Cygnus is "the swan", and Albireo is located at the head of the swan, it is sometimes called the "beak star". It also forms the "Northern Cross" along with Deneb, Delta Cygni and Eta Cygni .

The name of the star have come to originate by misunderstandings and wrong translations. The name of the star was originally al-Minhar al-Dajajah, "the hen's beak," as in Arab texts. Latin scholars misunderstood that the name had come from a kind of herb, and translated it into ab ireo ("from ireus"). Later, people considered it as a misprint of an Arabic term, and transcribed it as al-bireo.

Albireo is 385 light years away from the Earth. With bare eyes Albireo seems like a single star. However, when viewed with a telescope or spectacle, it readily resolves into a double star, one yellow (apparent magnitude 3.1), the other blue (apparent magnitude 5.1). Separated by 34 seconds of arc, the two components provide one of the best contrasting double stars in the sky due to their different colors.

They had been considered as merely optical double, not orbiting around a common point as a true binary star system would be. However, in spite of the large distance between them, it has been shown that they are a true binary system.

The brighter, yellow member of the pair, Beta Cygni A, is itself a close binary.