Koalib (also called Kwalib, Abri, Lgalige, Nirere and Rere) is a Niger–Congo language in the Heiban family spoken in the Nuba Mountains of southern Sudan. The Koalib Nuba, Turum and Umm Heitan ethnic groups speak this language.

Koalib dialects and locations (Ethnologue, 22nd edition):

It is written using the Latin script, but includes some unusual letters. It shares a tailed R (Ɽ) with other Sudanese languages, and uses a letter resembling the at sign (@) for transcribing the letter ع in Arabic loanwords. The Unicode Standard includes R WITH TAIL at code points U+027D (lowercase) and U+2C64 (uppercase), but the Unicode Consortium in 2004 declined to encode the at sign separately as an orthographic letter due to lack of evidence of use.

SIL International maintains a registry of Private Use Area code points in which U+F247 represents LATIN SMALL LETTER AT, and U+F248 LATIN CAPITAL LETTER AT. However, they have marked this PUA representation as deprecated since September 2014, and the current version of their corporate PUA character assignments package recommends using U+24D0 ⓐ CIRCLED LATIN SMALL LETTER A and U+24B6 Ⓐ CIRCLED LATIN CAPITAL LETTER A for that letter instead.

The New Testament was published in Koalib in 1967.^{[citation needed]}