Winged Messenger

One of the Nazgûl mounted on a flying creature, used by Sauron to carry messages and gather information during the War of the Ring. In the early days of that War, Sauron kept his Winged Messengers a secret, so that his enemies would not guess how quickly he could send and receive news. One of these Messengers was shot out of the sky by Legolas, but at that time its nature was unknown. It was the returned Gandalf who revealed the nature of the Winged Messengers to Aragorn and his allies.

The text of The Lord of the Rings can be interpreted to suggest that there was only one Winged Messenger, which would mean that one of the Nazgûl would have dedicated all of his time to carrying messages and news. As any the Nazgûl could fly when needed, it seems rather more likely that a Messenger was selected as a situation called for it, and that any of the Nine could play the part if Sauron called on them to do so.