Bay Ronald (foaled 3 May 1893) was a Thoroughbred racehorse that had a huge impact on the breeding of sport horses, mainly through his son Dark Ronald and grandson Teddy, and also carried on his lines in the Thoroughbred racing world, through his son Bayardo.

As a five-year-old he improved slightly, winning two out of seven starts: the City and Suburban Handicap (1¼ miles) and the Epsom Gold Cup, carrying 132 pounds.

Urged by thus success, his owner decided to enter him in the 2½ mile Ascot Gold Cup.

Due to his rather unimpressive record, his stud fee for the first season was 25 guineas, and free to mares who had already produced winners.

[3] In France, Bay Ronald produced some good horses, including Combourg, Greffulhe, Fidia and also Rondeau, the dam of the influential Teddy.

Dark Ronald is also featured in the pedigrees of Furioso, Beau Pere (progeny include international jumpers White Lightning and Encore (winner of the Grand Prix at Fontainebleau and a USET team member), eventer Landlady, two-time American invitational winner Sundancer, Canadian equestrian team member Easy Doc, and British equestrian team member Turn on the Sun), Der Loewe (in the pedigree of such horses as Salinero, Arko, and Brentina), and dressage stallion Bolero (sire of Brentano II, grand-sire of Poetin and Brentina).

Top eventers with Dark Ronald include Shear Leau and Bally Cor (both through Son-in-Law).

Bayardo produced English Triple Crown winner Gainsborough, who sired the small colt Hyperion.

Hyperion is found in the pedigrees of many sport horses, including the show jumpers Carling King, Jet Run, Pan American silver medalist A Little Bit, Encore (who also went back to Bay Ronald through Dark Ronald), Canadian equestrian team horse Stoic, Anne Kursinski's jumper Eros, and USET jumper Aberali.

He is also in the pedigree of eventers Charisma, Winsome Adante, Eagle Lion, Biko, and Sandrift, and the great sire of eventers Ben Faerie (sire of Priceless and Walk on Star, dam-sire of Primmore's Pride).