Hans Hollen Nielsen (born 26 December 1959) is a Danish former professional motorcycle speedway rider.

During his career, he won a total of 22 world championships, making him arguably the most successful speedway rider of all time.

Altogether he participated in winning 22 World Championships for Denmark (out of the 46 won by Danish riders/teams in all competitions to the end of 2014).

Nielsen and Sweden's Tony Rickardsson are the only 2 riders to have won world titles in both the old single meeting format and the Speedway Grand Prix series.

He was known as "The Main Dane" to fans, taking over the title from triple World Champion Ole Olsen, but was referred to as "The Professor" by his fellow riders due to his immaculate style and ability to ride speedway.

Denmark were the favourites to win again in 1989 at the Odsal Stadium in Bradford, but would eventually finish 3rd after the opening heat crash which ended the career and nearly took the life of Neilsen's friend, teammate and closest rival, triple World Champion Erik Gundersen.

1977 Nielsen aged just 17, signed for Wolverhampton Wolves for the 1977 British League season recording a healthy 7.25 average.

1978 Nielsen won his first Danish Championship and rode in the 1978 European Under-21 Final at the Pista Olimpia Terenzano in Lonigo, Italy where he finished 5th with 11 points.

1979 Nielsen won the World Pairs with Ole Olsen and finished runner-up to Jan Andersson in the Scandinavian final.

During the 1983 World Pairs Final at the Ullevi Stadium in Gothenburg, Sweden, Nielsen was involved in one of the more bizarre tape exclusions ever seen in speedway.

[9] 1985 Nielsen won the Danish final with a perfect 15 point maximum but finished runner-up once again to the defending champion Erik Gundersen in the 1985 Individual Speedway World Championship.

Fellow Dane Jan O. Pedersen took silver and England's Kelvin Tatum took the bronze while Gundersen faded into tenth place.

In a two-day final in Amsterdam, Nielsen trailed after day one by 1 point to Erik Gundersen and the American Sam Ermolenko.

However, in trademark style Nielsen produced a 15-point maximum on day two to wrap up the World Title, with Gundersen claiming silver and Ermolenko bronze.

[23] Nielsen joined fellow Danes Ole Olsen and Erik Gundersen as a three time Speedway World Champion.

[26] 1991 He won the bronze medal run-off beating Tommy Knudsen at the 1991 Individual Speedway World Championship in Gothenburg.

There was consolation in winning a sixth consecutive World Pairs (seventh in total and a record for any rider).

[29] 1993 Neilsen had another excellent performance in the 1993 Individual Speedway World Championship but was unable to win the fourth title he was seeking, he had to settle for the runner-up position behind Sam Ermolenko.

He was forced to leave his beloved Oxford Cheetahs following their decision not to compete in the top division, he joined the Coventry Bees.