| Leif Nielsen | |
| Fullname: | Leif Nielsen |
| Birth Date: | 31 March 1943 |
| Birth Place: | Copenhagen, Denmark |
| Position: | Forward |
| Youthclubs2: | BK Frem |
| Years1: | 1962–1972 |
| Clubs1: | BK Frem |
| Caps1: | 202 |
| Goals1: | 98 |
| Nationalyears1: | 1964–1965 |
| Nationalteam1: | Denmark U21 |
| Nationalcaps1: | 4 |
| Nationalgoals1: | 4 |
Leif Nielsen (born 31 March 1943) is a Danish former football (soccer) player, who played for Fremad Amager and BK Frem in Denmark. Nielsen was the top goalscorer of the 1967 Danish football championship. He played four games and scored four goals for the Denmark national under-21 football team.