Thora Feathermoon is one of 4 Alliance Outrunners who are scouting the Barrens. The others are Aean Swiftriver, Marcus Bel, and Hannah Bladeleaf. The mounted outrunners ride a patrol from Bael Modan in the south to the Lushwater Oasis in the north. The outrunners are elite fighters around level 25 and will fight together. Unless you are prepared or are high-level, Horde characters should keep their distance.
Possibly related to Shandris Feathermoon, General of the Sentinel Army.