Sagitta is a dim but distinctive constellation in the northern sky. Its name is Latin for 'arrow', not to be confused with the significantly larger constellation Sagittarius 'the archer'. It was included among the 48 constellations listed by the 2nd-century astronomer Ptolemy, and it remains one of the 88 modern constellations defined by the International Astronomical Union. Although it dates to antiquity, Sagitta has no star brighter than 3rd magnitude and has the third-smallest area of any constellation.

Gamma Sagittae is the constellation's brightest star, with an apparent magnitude of 3.47. It is an aging red giant star 90% as massive as the Sun that has cooled and expanded to a radius 54 times greater than it. Delta, Epsilon, Zeta, and Theta Sagittae are each multiple stars whose components can be seen in small telescopes. V Sagittae is a cataclysmic variable—a binary star system composed of a white dwarf accreting mass of a donor star that is expected to go nova and briefly become the most luminous star in the Milky Way and one of the brightest stars in our sky around the year 2083. Two star systems in Sagitta are known to have Jupiter-like planets, while a third—15 Sagittae—has a brown dwarf companion.

The ancient Greeks called Sagitta Oistos 'the arrow', and it was one of the 48 constellations described by Ptolemy. It was regarded as the weapon that Hercules used to kill the eagle (Aquila) of Jove that perpetually gnawed Prometheus' liver. Sagitta is located beyond the north border of Aquila, the Eagle. An amateur naturalist, polymath Richard Hinckley Allen proposed that the constellation could represent the arrow shot by Hercules towards the adjacent Stymphalian birds (which feature in Hercules' sixth labour) who had claws, beaks, and wings of iron, and who lived on human flesh in the marshes of Arcadia—denoted in the sky by the constellations Aquila the Eagle, Cygnus 'the Swan', and Lyra 'the Vulture'—and still lying between them, whence the title Herculea. Greek scholar Eratosthenes claimed it as the arrow with which Apollo exterminated the Cyclopes. The Romans named it Sagitta. In Arabic, it became al-sahm 'arrow', though this name became Sham and was transferred to Alpha Sagittae only. The Greek name has also been mistranslated as [ὁ istos] Error: {{Lang}}: Non-latn text (pos 1: ὁ)/Latn script subtag mismatch (help) 'the loom' and thus in Arabic al-nawl. It was also called al-'anaza 'pike/javelin'.

The four brightest stars make up an arrow-shaped asterism located due north of the bright star Altair. Covering 79.9 square degrees and hence 0.194% of the sky, Sagitta ranks 86th of the 88 modern constellations by area. Only Equuleus and Crux are smaller. Sagitta is most readily observed from the late spring to early autumn to northern hemisphere observers, with midnight culmination occurring on 17 July. Its position in the Northern Celestial Hemisphere means that the whole constellation is visible to observers north of 69°S. Sagitta is bordered by Vulpecula to the north, Hercules to the west, Aquila to the south, and Delphinus to the east. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is "Sge"; American astronomer Henry Norris Russell, who devised the code, had to resort to using the genitive form of the name to come up with a letter to include ('e') that was not in the name of the constellation Sagittarius. The official constellation boundaries, as set by Belgian astronomer Eugène Delporte in 1930, are defined by a polygon of twelve segments (illustrated in infobox). In the equatorial coordinate system, the right ascension coordinates of these borders lie between 18^h 57.2^m and 20^h 20.5^m , while the declination coordinates are between 16.08° and 21.64°.

Celestial cartographer Johann Bayer gave Bayer designations to eight stars, labelling them Alpha to Theta. English astronomer John Flamsteed added the letters x, mistaken as Chi (χ), y and z to 13, 14, and 15 Sagittae in his Catalogus Britannicus. All three were dropped by later astronomers John Bevis and Francis Baily.

Ptolemy saw the constellation's brightest star Gamma Sagittae as marking the arrow's head, while Bayer saw Gamma, Eta, and Theta as depicting the arrow's shaft. Gamma Sagittae is a red giant of spectral type M0 III, and magnitude 3.47. It lies at a distance of 258±4 light-years from Earth. With around 90% of the Sun's mass, it has a radius 54 times that of the Sun and is 575 times as bright. It is most likely on the red-giant branch of its evolutionary lifespan, having exhausted its core hydrogen and now burning it in a surrounding shell.

Delta Sagittae is the second-brightest star in the constellation and is a binary. Delta and Zeta depicted the spike according to Bayer. The Delta Sagittae system is composed of a red supergiant of spectral type M2 II that has 3.9 times the Sun's mass and 152 times its radius and a blue-white B9.5V main sequence star that is 2.9 times as massive as the Sun. The two orbit each other every ten years. Zeta Sagittae is a triple star system, approximately 326 light-years from Earth. The primary and secondary are A-type stars.

In his Uranometria, Bayer depicted Alpha, Beta, and Epsilon Sagittae as the fins of the arrow. Also known as Sham, Alpha is a yellow bright giant star of spectral class G1 II with an apparent magnitude of 4.38, which lies at a distance of 382±8 light-years from Earth. Four times as massive as the Sun, it has swollen and brightened to 21 times the Sun's radius and 340 times its luminosity. Also of magnitude 4.38, Beta is a G-type giant located 420±10 light-years distant from Earth. Estimated to be around 129 million years old, it is 4.33 times as massive as the Sun, and has expanded to roughly 27 times its radius. Epsilon Sagittae is a double star whose component stars can be seen in a small telescope. With an apparent magnitude of 5.77, the main star is a 331-million-year-old yellow giant of spectral type G8 III around 3.09 times as massive as the Sun, that has swollen to 18.37+0.65
−0.88 its radius. It is 580±10 light-years distant. The visual companion of magnitude 8.35 is 87.4 arcseconds distant, but is an unrelated blue supergiant around 7,000 light-years distant from Earth.