Alen Peternac (born 16 January 1972) is a Croatian retired footballer who played as a striker.
He is best known for his Real Valladolid stint, having spent the better part of his professional career in Spain, appearing in 206 official games in representation of three clubs.
Peternac was born in Zagreb, Socialist Federative Republic of Yugoslavia. In 1989 he started his football career at hometown NK Dinamo Zagreb, and played six years for Dinamo and HNK Segesta in the Croatian league before moving to Spain.
Peternac spent five seasons at Real Valladolid, appearing in 171 competitive games and becoming the team's all-time top goalscorer in La Liga. His goal total also made him the second-highest Croatian goalscorer in the competition, behind Sevilla FC and Real Madrid's Davor Šuker.
On 19 May 1996, in an 8–3 away win against Real Oviedo which proved crucial in helping Valladolid avoid direct relegation in 1995–96, Peternac set a club record by netting five times, four of which on penalty kicks. He finished that campaign as the fourth top goalscorer, with 23 goals.
For 2000–01, Peternac joined Real Zaragoza, receiving limited playing time. He was then loaned to Real Murcia, where he played one season in the second division before closing out his career back with the Aragonese (one match, followed by retirement due to injuries).
Peternac earned his first cap for Croatia on 10 February 1999 against Denmark, in a friendly played in Split (0–1). Exactly one month after he appeared in another exhibition game, now with Greece (2–3); incidentally, he replaced then was replaced by Goran Vlaović in his two appearances, at half-time.