NGC 6558 is a globular cluster, located about 24,000[4][a] light years away in the constellation Sagittarius.

Its apparent magnitude is about 11 and its apparent diameter is about 10 arcminutes.

[2] The globular cluster was discovered in 1784 by the astronomer William Herschel with his 18.7-inch telescope and the discovery was later catalogued in the New General Catalogue.

It is located 1.5 degrees south-southeast of Gamma2 Sagittarii.

This star cluster–related article is a stub.