| Mario Killer | |
| Fullname: | Mario Estanislao Killer Díez |
| Birth Date: | 15 August 1951 |
| Birth Place: | Rosario, Santa Fe, Argentina |
| Position: | Defender |
| Years1: | 1971–75 |
| Years2: | 1975–78 |
| Years3: | 1978–79 |
| Years4: | 1979–80 |
| Years5: | 1980–83 |
| Years6: | 1984 |
| Years7: | 1985 |
| Clubs1: | Rosario Central |
| Clubs2: | Sporting de Gijón |
| Clubs3: | Real Betis |
| Clubs4: | Newell's Old Boys |
| Clubs5: | Independiente |
| Clubs6: | Rosario Central |
| Clubs7: | Belgrano |
| Caps1: | 150 |
| Goals1: | 2 |
| Caps2: | 70 |
| Goals2: | 2 |
| Caps3: | 25 |
| Goals3: | 0 |
| Caps4: | 10 |
| Goals4: | 0 |
| Caps5: | 169 |
| Goals5: | 0 |
| Caps7: | 6 |
| Goals7: | 0 |
| Nationalyears1: | 1972–75 |
| Nationalcaps1: | 5 |
| Nationalgoals1: | 2 |
| Nationalteam1: | Argentina |
| Club-Update: | 27 May 2014 |
Mario Estanislao Killer Díez (born 15 August 1951) is an Argentine retired footballer. He played as defender in different clubs in Argentina and Spain[1] and was part of the national team at the 1975 Copa América, where he scored 2 goals in the group stage in Argentina's 11–0 win over Venezuela.[2]