Hawk Mountain is the fourth foal of Hydrangea (Galileo), a dual Group 1 winner in England and Ireland whose wins included the Gr.1 Matron Stakes over a mile and the Gr.1 British Champions Fillies & Mares Stakes over a mile and a half. Her other runners are Wingspan (Dubawi), winner of the Listed Hurry Harriet Stakes and second in the Gr.1 British Champions Fillies & Mares Stakes, and Officer (Dubawi), winner of the Listed Tetrarch Stakes.

Second dam Beauty Is Truth (Pivotal), herself a Group 2 winner, is also the dam of the Group 1 winners The United States and Hermosa, both full siblings to Hydrangea. The United States won the Gr.1 Ranvet Stakes. Hermosa won the Gr.1 1000 Guineas and the Gr.1 Irish 1000 Guineas and produced Trinity College (Dubawi), winner of the Gr.3 Hampton Court Stakes and second in the Gr.1 Grand Prix de Paris. Her other winners include Fire Lily (Dansili), twice a Group 3 winner and twice placed at Group 1 level, and Salsa (Galileo), a winner at three and the dam of Whirl (Wootton Bassett), winner of the Gr.1 Nassau and the Gr.1 Pretty Polly.

Third dam Zelding (Warning) won the Gr.3 Prix du Bois and was twice placed at Group 2 level. Among her nine other winners is Glorious Sight (Singspiel), a Listed winner and runner-up in the Gr.1 Poule d'Essai des Pouliches. She in turn is the dam of Glycon, winner of the Gr.2 Grand Prix de Deauville and placed at Group 1 level, and of the Listed winner Glaer.

This is the family of Last Tycoon and Zipping.

Hydrangea has a yearling full brother to Hawk Mountain and a colt foal by Justify, and she has been covered again by Justify for 2026.