Kauto Star (19 March 2000 – 29 June 2015) was a French-bred National Hunt champion thoroughbred racehorse trained by Paul Nicholls in Somerset and owned by Clive Smith.

Kauto Star was one of the most successful steeplechasers of any era: he finished his career with a National Hunt record of £3,775,883 in earnings, £2,375,883 of which was winner's prize money,[3] a £1,000,000 bonus for the completion of the 2006/2007 Stayers Chase Triple Crown and a £400,000 reward for heading the BHA Table of Merit in the 2006/2007 season.

His sire was the Grand Prix de Saint-Cloud winner Village Star and his dam was Kauto Relka, who was a daughter of Port Etienne.

He was passed by Mistral De La Cour, but Kauto Star's jockey Ruby Walsh then re-mounted without his stirrups and chased the leader.

He then hit the last fence, but still rapidly closed in on the finishing straight and lost out to Mistral De La Cour by a short-head.

[8] Kauto Star started the 2005/06 season in the Haldon Gold Cup at Exeter, where he finished in second place, four lengths behind Monkerhostin.

[10] After this victory, he was sent off as the 2/1 favourite for the Queen Mother Champion Chase at the Cheltenham Festival in a field that included Moscow Flyer.

After taking the lead with three fences left to jump, he again pulled clear to easily win by 7 lengths from Voy Por Ustedes.

Kauto Star had an additional challenge to face during the 2007/08 as another of Paul Nicholls' horses, Denman, had easily won the Royal & SunAlliance Chase, the top race for novice 3 mile chasers, at the previous season's Cheltenham Festival when also ridden by Ruby Walsh.

Nicholls stated his intention to keep the pair apart for the majority of the season, with the two horses not scheduled to race against each other until the Cheltenham Gold Cup in March.

[18] Kauto Star continued to follow the same path as last season and next started in the Betfair Chase, where he was ridden by Sam Thomas due to regular jockey Ruby Walsh being out injured with a dislocated shoulder.

With Walsh back in the saddle, he won by 11 lengths from Ascot Chase winner Our Vic, with Exotic Dancer in third place.

Paul Nicholls revealed that his vet had examined Kauto Star that morning and that the horse appeared to have an infection in one of his hind feet.

Horse racing fans were awaiting the 2008 Cheltenham Gold Cup clash between Kauto Star and his stablemate Denman.

Denman took up the race to lead with a circuit to go and won by 7 lengths with Kauto Star finishing second, just holding off stablemate Neptune Collonges.

[22] Kauto Star narrowly lost his last race of the season to Ryanair winner Our Vic in the Totesport Bowl at Aintree.

Kauto Star's owner, Clive Smith, put the defeat down to the horse's busy season and also the short time since the Cheltenham Gold Cup.

After Kauto Star's defeat following the short break between the races at Down Royal and Haydock, Nicholls stated he had come to the conclusion that the horse was best run fresh, so unlike previous seasons he would not run again before Cheltenham where he was once again being aimed at the Cheltenham Gold Cup, as was stable companion and current holder Denman.

The leaders in the betting were Kauto Star at 7/4, Denman at 7/1, Hennessy Gold Cup winner Neptune Collonges at 15/2 and Exotic Dancer at 8/1.

[28] On Boxing Day 2009 at Kempton Park, Kauto Star attempted to win his fourth consecutive King George VI Chase.

He was given a Timeform rating of 191, the highest given to a horse in almost 40 years and making him the joint-third highest-rated steeplechaser of all time, level with Mill House and behind only Arkle (212) and Flyingbolt (210).

[32] His next race was an attempt to win a record-breaking fifth consecutive King George VI Chase in a meeting which was rearranged to mid-January after the original Boxing Day fixture was postponed due to snow.

Calls for Kauto Star's retirement grew more vociferous, although connections stated their intention to bring him back into training after the summer break and assess the horse's condition before aiming him for another race if they were satisfied with his physical and mental wellbeing.

On Saturday 19 November 2011, Kauto Star lined up for the Betfair Chase at Haydock Park, having pleased his trainer and work rider with his enthusiasm on his return to training.

Ridden prominently by usual partner Ruby Walsh, Kauto Star made it four victories in the race, having previously won it in 2006, 2007 and 2009.

He won by eight lengths from favourite Long Run, turning the tables on his Gold Cup and King George conqueror of the previous season.

"[37] On Boxing Day, Kauto Star lined up for the King George VI Chase for the sixth year in succession.

At the end of February 2012, Paul Nicholls announced that Kauto Star had suffered an "awful fall" during a routine schooling session at his training yard, putting his participation in the Gold Cup in doubt.

Clive Smith said of Nicholls: "He is trying emotional blackmail, saying that Kauto Star would be better off staying at Ditcheat to be Clifford Baker's hack.

After receiving intensive medical treatment over the weekend at the Valley Equine Hospital, the multiple injuries proved too severe and on Monday 29 June, 3 pm BST the horse was humanely euthanized, veterinary assistant Hattie Lawrence reporting "Three bones appear to have been fractured...