Sraosa, whose name means "listening" or "harkening", was the messenger god of the Achaemenid Persian empire. He served the supreme god, Ahura Mazda, as part of the latter's personal retinue, the Amesha Spentas. He was well-known as an embodiment of obedience in this capacity. This meant that Sraosa's arch-enemy was one of the seven Daevas (there was one Daeva, sort of a second-in-command evil spirit, for each of the seven Amesha Spentas, who were the second-in-command good spirits), namely Aesma Daeva. The rooster and his crowing were sacred to Sraosa, as was the 17th day of any given month. Probably related to his fondness for roosters was one of his other duties, dispelling the darkness and wiping away the stars at dawn. He also rode around in a chariot pulled by four reddish horses, and was kind of the cleancut, athletic go-getter type.
One of Sraosa's other duties was to conduct the souls of the dead to the afterlife, in which capacity he was aided by another sky god called Bahram. In this duty as well as his status as a messenger, Sraosa may well have served as a model or influence for the later and better-known Greco-Roman god, Hermes/Mercury. It should, however, be noted that the latter was famous as a trickster and thief, qualities that run directly counter to any spirit of obedience. Sraosa is also occasionally identified with the hero figure Skanda from Hindu mythology.
Sources: http://www.pantheon.org/articles/s/sraosa.html, http://www.geocities.com/cas111jd/persia/persia_ls.htm,http://groups.yahoo.com/group/vediculture/message/1027