Mark Letestu (born February 4, 1985) is a Canadian former professional ice hockey forward and current head coach of the American Hockey League’s Colorado Eagles. He played in eleven seasons of the National Hockey League (NHL) for the Pittsburgh Penguins, Columbus Blue Jackets, Edmonton Oilers and Winnipeg Jets.

Letestu played three seasons of junior hockey with the Bonnyville Pontiacs of the Alberta Junior Hockey League (AJHL). During the 2005–06 season, Letestu led the AJHL in scoring with 105 points (50 goals and 55 assist) in 58 games and was named the AJHL's most valuable player.

Letustu then played the 2006–07 season at Western Michigan University of the Central Collegiate Hockey Association (CCHA). Amongst players throughout the entire NCAA, Letestu finished the season 6th in goals, 14th in points and 1st in short-handed goals with five.

After playing at Western Michigan, Letestu was signed as an undrafted free agent by the NHL's Pittsburgh Penguins on March 22, 2007. He appeared in three regular and two playoff games with the Wilkes-Barre/Scranton Penguins, Pittsburgh's American Hockey League (AHL) affiliate, when he joined the team at the end of the 2006–07 season. In 2007–08 he appeared in 52 games with Wilkes-Barre/Scranton and six games with the Wheeling Nailers of the ECHL. He then spent the entire 2008–09 season in the AHL. In March 2009, Letestu signed a new two-year contract with the Penguins.

Letestu made his NHL debut on November 14, 2009, against the Boston Bruins. He made another appearance with the Penguins before being reassigned to Wilkes-Barre/Scranton. Letestu was called up again on December 5 and played that night against the Chicago Blackhawks. He received 13:52 of ice time and won a faceoff against John Madden that set up the game's tying goal by Jordan Staal with 31 seconds remaining in the game.

Letestu scored his first career NHL goal on February 1, 2010, against Ryan Miller of the Buffalo Sabres, scoring 47 seconds into the first period; the goal was assisted by Tyler Kennedy and Kris Letang. Letestu was one of seven Wilkes-Barre/Scranton players recalled by Pittsburgh after the AHL Penguins were eliminated in the first round of the 2010 Calder Cup playoffs. He appeared in his first Stanley Cup playoff game in the Penguins' second round series against the Montreal Canadiens on May 4 when he replaced the injured Staal as the third-line centre between Tyler Kennedy and Matt Cooke. In Game 5 on May 8, Letestu recorded his first Stanley Cup playoff point with an assist on a second period goal by Sergei Gonchar.

Letestu began the 2010–11 season with the Penguins after delivering a strong training camp and pre-season. He finished the pre-season with one goal and five assists in five games. After scoring against the Chicago Blackhawks during pre-season, Letestu said, "I worked hard this summer... the praise is nice but it's only as good as your last game. I just need to keep playing the way I have been and hopefully force somebody to keep me here." He began the 2010–11 NHL regular season equally as strong, scoring game-winning goals in two of his first three games, being named one of the Stars of the Game against Montreal and the New Jersey Devils. Letestu was then named the first star against the Ottawa Senators on October 18, 2010, after scoring a power-play goal and assisting on Evgeni Malkin's goal by winning a faceoff in the Ottawa zone. The performance gave him seven points in his first seven games. Of Letestu, Penguins captain Sidney Crosby said, "He has really made an impact for us."

However, Letestu's production dipped into November, as he went 22 consecutive games without scoring a goal. On December 8, 2010, Letestu broke his scoring drought with the first multi-goal game of his NHL career, scoring twice against the Toronto Maple Leafs. On January 18, 2011, Letestu signed a new two-year contract with the Penguins worth an average annual value of $625,000. At the time, he was tenth among all NHL rookies in scoring (19 points) and had scored three game-winning goals.