Song, LLC, was a low-cost air service within an airline brand owned and operated by Delta Air Lines from 2003 to 2006. All Song flights were operated by Delta. Song's main focus was on leisure traffic between the Northeastern United States and Florida, a market where it competed with JetBlue Airways. It also operated flights between Florida and the West Coast, and from the Northeast to the West Coast.

Delta Express was a no-frills "airline within an airline" brand owned and operated by Delta Air Lines from 1996 to 2003. The airline was headquartered in Atlanta, Georgia.