Royal Delta (February 2, 2008 – February 10, 2017) was a Champion American Thoroughbred racehorse. The daughter of Empire Maker was best known for winning back-to-back editions of the Breeders' Cup Ladies Classic (later renamed the Breeders' Cup Distaff) and three consecutive Eclipse Awards (as American Champion Three-Year-Old Filly of 2011 and American Champion Older Female Horse of both 2012 and 2013). She won the Grade I Alabama, Beldame, Delaware and Personal Ensign Stakes in addition to her Breeders' Cup triumphs.

On February 10, 2017, it was announced that she had died due to foaling complications.

On April 22, 2019, Royal Delta was voted into the National Museum of Racing Hall of Fame.

Royal Delta was a dark bay mare with a white star and a white sock on her left hind leg. She was bred in Kentucky by Prince Saud bin Khaled's Palides Investments. She was sired by Empire Maker, who had won the 2003 Belmont Stakes winner. Prior to Royal Delta, Empire Maker's most successful offspring was Pioneerof the Nile, who placed second in the Kentucky Derby and became the sire of Triple Crown winner American Pharoah. Royal Delta was from Empire Maker's fourth crop and started racing shortly after her sire was exported to Japan.

Royal Delta's dam was Delta Princess, a stakes winning mare by A.P. Indy. Ron Wallace, general manager of Palides, explained the difference between mother and daughter in a 2011 interview: "(Delta Princess) is tough; she's a lot more competitive than Royal Delta. But Royal Delta is way more athletic and she hasn't even quite figured it all out. She is going to be incredible as a 4-year-old. She was laid back in the paddock (before racing in the 2011 Ladies' Classic). Here (at the Keeneland Sales), she's a star, but she doesn't care. Her mother would eat horses alive in front of her; she was going to win no matter what. Royal Delta is just good (because of her natural ability). If she learns to be competitive, watch out."

Royal Delta initially raced as a homebred for Palides Investments. Prince Saud bin Khaled died in 2011, and Royal Delta was sold at a dispersal sale to Besilu Stables.

Royal Delta stood 16.2 hands (66 inches, 168 cm) high at the withers. She was trained throughout her career by Bill Mott, who described her as determined and willful. Although a high energy horse, she usually maintained a level attitude on the racetrack. She had a large appetite and was known around the stable simply as "Royal".

Royal Delta made her debut in a one-mile maiden special weight race on October 30, 2010 at Belmont Park, which she won by 12 lengths.