Darius I (550-486 BC) claims credit for the invention of Old Persian Cuneiform in an inscription on a cliff at Behistun in south-west Iran. The inscription dates from 520 BC and is in three languages - Elamite, Babylonian and Old Persian. Some scholars are sceptical about Darius' claims, others take them seriously, although they think that Darius probably commissioned his scribes to create the alphabet, rather than inventing it himself.
Old Persian, the language used in the cuneiform inscriptions of Achaemenian dynasty and the vernacular of the Achaemenian elite. Old Persian was spoken in southwestern Persia, an area known as Persis, and belongs to the Iranian branch or the Indo-Aryan family of languages.
This is part of the Behistun inscription (column 1, lines 1-8).
\ adam \ Dârayavauš \ xšâyathiya \ vazraka \ xšâyatha \ xšâyathiy ânâm \ xšâyathiya \ Pârsaiy \ xšâyathiya \ dahyânâm \ Višt âspahyâ \ puâa \ Aršâmahyâ napâ \ Haxâmanišiya \ thâtiy \ Dârayavauš \ xšâyathiya \ manâ \ pitâ \ Vištâspa \ Vištâspahyâ \ pitâ \ Arš âma \ Aršâmahyâ \ pitâ \ Ariyâramna \ Ariyâramnahyâ \ pitâ\ Cišpiš \ Cišp âiš \ pitâ \ Haxâmaniš \ thâtiy \ Dârayavauš \ xšâthiya \ avahyarâ diy \ vayam \ Haxâmanišiyâ \ thahyâmahy \ hacâ \ paruviyata \ âmâtâ \ ama hy hacâ \ paruviyata \hyâ \amâxam \ taumâ \ xšâyathiyâ \ âha \ th
(1) I am Darius, the great king, king of kings, the king of Persia, the king of countries, the son of Hystaspes, the grandson of Arsames, the Achaemenid.
(2) King Darius says: My father is Hystaspes; the father of Hystaspes was Arsames; the father of Arsames was Ariaramnes; the father of Ariaramnes was Teispes; the father of Teispes was Achaemenes.
(3) King Darius says: That is why we are called Achaemenids; from antiquity we have been noble; from antiquity has our dynasty been royal.
Details of the Old Persian script and language
Old Persian cuneiform fonts
Circle of Ancient Iranian Studies at the School of Oriental and Asian Studies (SOAS), University of London: http://www.cais-soas.com/
ALPHABETUM - a Unicode font specifically designed for ancient scripts, including classical & medieval Latin, ancient Greek, Etruscan, Oscan, Umbrian, Faliscan, Messapic, Picene, Iberian, Celtiberian, Gothic, Runic, Old & Middle English, Hebrew, Sanskrit, Old Nordic, Ogham, Kharosthi, Glagolitic, Old Cyrillic, Phoenician, Avestan, Ugaritic, Linear B, Anatolian scripts, Coptic, Cypriot, Brahmi, Old Persian cuneiform: http://guindo.pntic.mec.es/~jmag0042/alphabet.html