| Mladen Košćak | |
| Birth Date: | 16 October 1936 |
| Birth Place: | Zagreb, Kingdom of Yugoslavia |
| Death Place: | Zagreb, Croatia |
| Position: | Defender |
| Years1: | 1955–1963 |
| Caps1: | 76 |
| Goals1: | 0 |
| Nationalyears1: | 1956 |
| Nationalteam1: | Yugoslavia |
| Nationalcaps1: | 4 |
| Nationalgoals1: | 0 |
Mladen Košćak (16 October 1936 – 3 August 1997) was a Croatian footballer.
Born in Zagreb, Košćak joined the youth academy of local side Dinamo Zagreb, with whom he spent his entire career.[1] He started playing at full professional level in the 1955–56 season. Košćak soon established himself as a first-team regular and was instrumental in Dinamo's 1957–58 Yugoslav First League title. Although he was considered a huge talent, his career was hampered by a serious injury and he effectively stopped playing by 1960, appearing in only a single match in his last three years with the club before retiring in 1963.[1]
Internationally, he was capped 4 times for the Yugoslavia national football team and was member of the national squad which won the silver medal at the 1956 Summer Olympics in Melbourne.[2] [3] His final international was a December 1956 friendly match away against Indonesia.[4]