Luca Castellazzi (born 19 July 1975) is an Italian footballer who plays as a goalkeeper for Serie A club Internazionale.

Early career
He started his career at Monza. He then spent time in Serie B, Serie C1 and Serie C2 with Padova and Pescara, before joining Brescia along with Vincenzo Mazzeo.

Brescia
Castellazzi followed Brescia promoted to Serie A in summer 2000. He made his Serie A debut on 21 January 2001, against Vicenza Calcio. In 2001-02 season, he was the starting keeper for the Serie A team, but in next season lost his place to Matteo Sereni. After being loaned to Reggina and Catania in the 2002–03 season, he finally became regular starter again in the 2004–05 season, which he played all 38 Serie A games. Castellazzi initially the first choice of 2003-04 season, but lost his place to Federico Agliardi after round 4 and regained his place on round 23.

Sampdoria
After Brescia were relegated to Serie B in summer 2005, he joined U.C. Sampdoria on a free transfer, signing a reported 2 year deal. He received the no.1 shirt from Luigi Turci. The first season he was the backup of Francesco Antonioli, and Castellazzi only played the 3 games that Antonioli missed.

In the second season, he finally earned a regular place, and in January 2008, he signed a contract extension again which would run until summer 2010. After the injury during 2009-10 season, he lost his regular place to Marco Storari and in February rumoured he signed a pre-contract with Internazionale.

In total, he played 101 league matches for the Genoese side, while his understudy Antonio Mirante, Gianluca Berti and Carlo Zotti played 22 matches during 2007-08 to 2008-09 season, 11 matches and 1 match in 2006-07 respectively.

Internazionale
On 17 June 2010 Castellazzi joined UEFA Champions League and Serie A champions F.C. Internazionale Milano on a free transfer tying him to Inter until 2012. He became one of the understudies to Júlio César along with Paolo Orlandoni and replaced the retired Francesco Toldo. In 2010-2011 Castellazzi played in all three major competitions, Serie A, Champions League and Coppa Italia, due to injuries to Julio Cesar.