The Proto-Kartvelian language, or Common Kartvelian (Georgian: წინარექართველური ენა, romanized: ts'inarekartveluri ena, Georgian: პროტოქართველური ენა, romanized: p'rot'okartveluri ena), is the linguistic reconstruction of the common ancestor of the Kartvelian languages, which was spoken by the ancestors of the modern Kartvelian peoples. The existence of such a language is widely accepted by specialists in linguistics, who have reconstructed a broad outline of the language by comparing the existing Kartvelian languages against each other.^[1] Several linguists, namely, Gerhard Deeters and Georgy Klimov have also reconstructed a lower-level proto-language called Proto-Karto-Zan or Proto-Georgian-Zan, which is the ancestor of Karto-Zan languages (includes Georgian and Zan).^[2]

The ablaut patterns of Proto-Kartvelian are highly similar to those of the Indo-European languages, and so it is thought that Proto-Kartvelian interacted with Indo-European at a relatively early date.^[3] This is reinforced by cognates with Indo-European, such as the Proto-Kartvelian *mḳerd- (breast), and its possible relation to the Proto-Indo-European *ḱerd- (heart). Proto-Kartvelian *ṭep- (warm) may also be related to Proto-Indo-European *tep- "warm".^{[1][better source needed]}

The modern descendants of Proto-Kartvelian are Georgian, Svan, Mingrelian and Laz. The ablaut patterns of Proto-Kartvelian were better preserved in Georgian and (particularly) Svan than in either Mingrelian or Laz, in which new forms have been set up so that there is a single, stable vowel in each word element.^[1]

The system of pronouns of Proto-Kartvelian is distinct on account of its category of inclusive–exclusive (so, for instance, there were two forms of the pronoun "we": one that includes the listener and one that does not). This has survived in Svan but not in the other languages. Svan also includes a number of archaisms from the Proto-Kartvelian era, and therefore it is thought that Svan broke off from Proto-Kartvelian at a relatively early stage: the later Proto-Kartvelian stage (called Karto-Zan) split into Georgian and Zan (Mingrelo-Laz).^[1]