Manuella (1809 – after 1831) was a British Thoroughbred racehorse and broodmare who won the classic Oaks Stakes at Epsom Downs Racecourse in 1812.

She is regarded as the foundation mare of Thoroughbred family 11-g.[4] Manuella made her first appearance in the Derby Stakes at Epsom on 14 May.

She "made but little running"[5] and finished unplaced behind Octavius, Lord Egremont's unnamed Gohanna colt and the favourite Comus.

[6] There were rumours that Chifney had "pulled" Manuella (deliberately prevented her from winning) in order to ensure better odds for the Oaks on the following day.

Peirse, riding with what was described as "uncommon judgement"[7] eased the filly down early in the straight and allowed Chifney, on the Duke of Rutland's Elizabeth, the odds-on favourite, to move up alongside him.

[9] Three days later, Manuella ran in a sweepstakes for three-year-old fillies over the same course and distance and "won easy"[10] from Mother Bunch and Pope Joan.

On 12 April at the Craven meeting she contested the second class of the Oatlands Stakes, a handicap race over the two mile "Ditch-In" course.

In 1830, Manuella produced Belzoni's full brother Belshazzar, who had some success as a racehorse and sired the 1000 Guineas winner Cara.

Margellina's descendants include War Admiral, Sun Cap (Epsom Oaks), Zeddaan (Poule d'Essai des Poulains), Enterprise (2000 Guineas), Eight Thirty and Stop The Music.