Pelasgian

Pelasgian is an extinct ancient language (or languages) that according to Ancient Greek and Ancient Roman sources existed in limited areas of Ancient Greece during the 2nd and 1st Millennium BC.
Herodotus
Herodotus called it "Barbarian" language but not the Pelasgians (it's speakers).
Official origin
It's origin and it's form are officially unknown because no Pelasgian literature examples survived.
Modern theories
The 2 main modern theories about the Pelasgian language suggest that it was a Greek dialect that saw extensive changes or that it was a Western Anatolian language.
Other Theories
A Bulgarian linguist suggested that the Pelasgians were speaking Thracian. In addition he suggested that the Pelasgians were a sub group of the mysterious late Bronze Age Sea Peoples that caused chaos in the Mediterranean and attacked several cities in the Aegean Sea. This theory has been rejected by most researchers.
Obsolete theories
During the 19th Century an Austrian diplomat and Albanian speaker suggested a connection between Early Albanian and Pelasgian. Similar claims have been made by modern Albanian nationalistic organizations. This type of theories have been rejected by modern scholars