Mimi (1888 – 1907) was a dual classic-winning British Thoroughbred racehorse and broodmare. As a two-year-old in 1890 she showed very promising form to win her first four starts but was well beaten when stepped up in class to contest the Middle Park Plate and the Dewhurst Plate. She established herself as the best filly of her generation in May 1891 with three wins in 26 days, taking the 1000 Guineas over one mile, the Newmarket Stakes over ten furlongs and the Oaks Stakes over 1+1⁄2 miles. She was subsequently beaten in the Prince of Wales Stakes at Leicester and was no match for Common in the St Leger. She was retired from racing at the end of the year and went on to have some success as a dam of winners.

Mimi was a brown mare bred by Tatton Sykes at his Sledmere Stud, near Driffield in Yorkshire. As a yearling she was consigned to the sales at Doncaster and was bought for 1000 guineas on behalf of Noel Fenwick. The filly was sent into training with the semi-retired veteran Mathew Dawson at his Melton House stable in Newmarket, Suffolk.

Mimi's sire was the undefeated Irish champion Barcaldine, a representative of the Godolphin Arabian sire line, who also sired the Epsom Derby winner Sir Visto and the influential sire Marco. Her dam, an unnamed mare sired by Lord Lyon, also produced Priestess, the dam of Nun Nicer.

Mimi began her racing career with four consecutive wins. She took the Lavant Stakes at Goodwood Racecourse, the Zetland Stakes (not the current race of the same name) at Newmarket Racecourse and the Two-Year-Old Stakes at the latter track.

On 7 October, over six furlongs at Newmarket, Mimi won the Clearwell Stakes at odds of 1/8, beating the colt Woolthorpe (her only opponent) by three quarters of a length. On the following day over the same course and distance Mimi started at odds of 7/1 the Middle Park Plate, which was then the most prestigious two-year-old race of the season, and sustained her first defeat as she came home fifth behind the French-bred colt Gouverneur. At the next Newmarket meeting three weeks later she ran disappointingly when coming home last of five behind Lord Rosebery's filly Corstorphine (also trained by Dawson) in the seven furlong Dewhurst Plate, with press reports suggesting that she had failed to stay the longer distance. She ended the year with earnings of £1,887.

Fenwick put his filly up for auction at Newmarket in autumn, but she failed to reach her reserve price of 5,500 guineas.

On 1 May, ridden by Fred Rickaby, Mimi was one of 12 fillies to contest the 78th running of the 1000 Guineas over the Rowley Mile course. She started the 7/1 third choice in the betting behind Siphonia (who had finished ahead of her when runner-up in both the Middle Park and the Dewhurst) and Lord Ellesmere's Belvidera. She had been available at 10/1 shortly before the race but her odds shortened after several large wagers were placed by her owner, Noel Fenwick. Mimi led from the start turned back a challenge from her stablemate Melody and won "easily" by 1+1⁄2 lengths, with Siphonia three lengths back in third place. Her winning time of 1:44.2 seconds was almost three seconds faster than that recorded by Common in the 2000 Guineas over the same course two days earlier.

Twelve days later Mimi was moved up in distance and matched against male opposition in the Newmarket Stakes over ten furlongs for which she started 9/2 second favourite behind the Duke of Westminster's highly regarded colt Orion. Melody set the pace with Mimi, ridden by John Watts settling in second place before going to the front in the last quarter mile. She won with "cleverly" by three quarters of a length from Melody with the colt St Simon of the Rock taking third ahead of Orion.