RETNA (born Marquis Lewis in 1979) is an American artist noted for his grafitti and paintings which display distinctive scripts of characters from his invented written language.

The artist cites diverse influences such as medieval illuminated manuscripts as sources towards his development of a constructed script which he uses in much of his work. Each block of text is a system of hieroglyphs and calligraphic script influenced by Arabic calligraphy, Egyptian hieroglyphs, Hebrew, Blackletter and Native American typographies. Retna's script communicates personal messages and poetry which are not immediately decipherable to the viewer.

In 1996, he chose the name RETNA from a Wu-Tang Clan lyric. In 2012, RETNA was commissioned by the fashion design firm Louis Vuitton to create signage for their temporary Miami Design District boutique. The project was a collaboration with street artists Aiko and Os Gêmeos, and included the design of scarves and accessories. In 2015, he designed the artwork for Justin Bieber's album "Purpose".

RETNA is regarded as one of the most recognised street-culture artists in the world.