Below is a sampling of languages that have been claimed to exist in reputable sources but have subsequently been disproved or challenged.
Others are honest errors that persist in the literature despite being corrected by the original authors; an example of this is Hongote, the name given in 1892 to two Colonial word lists, one of Tlingit and one of a Salishan language, that were mistakenly listed as Patagonian.
The error was corrected three times that year, but nonetheless "Hongote" was still listed as a Patagonian language a century later in Greenberg (1987).
(In some cases, however, the evidence for nonexistence is a survey among the current population of the area, which would not identify extinct languages such as Ware below.)
Glottolog, maintained at the Max Planck Institute for Evolutionary Anthropology in Leipzig, classifies several languages, some with ISO 639 codes, as spurious/unattested in addition to those retired by the ISO.