Oskar Sundqvist (born 23 March 1994) is a Swedish professional ice hockey player who is a centre for the St. Louis Blues of the National Hockey League (NHL).

Born in Boden, Sweden, Sundqvist played within the Skellefteå organization at both their club youth and professional levels. After being drafted in the third round, 81st overall, of the 2012 NHL entry draft by the Pittsburgh Penguins, Sundqvist won a silver medal with Sweden junior team at the 2014 World Junior Championships.

Upon moving to North America, Sundqvist spent three seasons within the Penguins organization, with whom he won the 2016 Stanley Cup. In 2017, he was traded to the Blues and helped them win their first Stanley Cup in franchise history.

Sundqvist was born on 23 March 1994 in Boden, Sweden. Growing up in Sweden, Sundqvist played within the Skellefteå organization in their club youth levels. He chose to play for Skellefteå after the hockey gymnasium school in Luleå showed little interest. Sundqvist recorded 22 goals and 54 points in 41 games with the Skellefteå's Junior team before being drafted in the third round, 81st overall, by the Pittsburgh Penguins in the 2012 NHL entry draft. The Penguins were originally skeptical of Sundqvist due to his size and lack of visibility due to his location, but conceded after encouragement from European scout Tommy Westlund. Penguins assistant director of amateur scouting Randy Sexton praised Sundqvist following the draft by saying "He's big, he's rangy, he skates and plays very hard. He's got good hands close to the net and he can finish. He's a Penguin." After his selection, Sundqvist was invited to the Penguins' Prospect Development Camp before returning to his home country where he made his Swedish Elite League (SEL) debut with Skellefteå on 24 October 2012 against Frölunda HC. He scored his first career SHL goal in a game against Frölunda HC on 5 January 2013. He completed his rookie campaign with the team recording one point in 14 games.

During the summer prior to the 2013–14 season, Sundqvist was invited to participate in the Penguins' Prospect Development Camp at the Consol Energy Center. He also joined the team for their preseason games, during which head coach Mike Johnston said "He's a very good prospect... He's got size, he's good both ways, he's responsible, so he's going to be a very good player for this organization." Upon returning to his home country for the season, Sundqvist was selected to compete with Sweden men's national junior ice hockey team at the 2014 World Junior Ice Hockey Championships. He scored the game-winning goal in the third period against Russia to help send Sweden to the gold medal round against Finland, although they ended the tournament with a silver medal. He returned to Skellefteå where he helped them win the 2014 Swedish Championship by recording six points in 13 playoff games.

Following the conclusion of the SHL season, the Penguins signed Sundqvist to a three-year, entry-level contract. After attending the Penguins training camp, he was returned to Skellefteå AIK on 7 October 2014 for the 2014–15 season. In his last season in the Swedish league, Sundqvist recorded a career high nine goals and 19 points, but was often recovering from injuries. During a game in December, Sundqvist took a puck to the wrist and was forced to leave a game early. A few months later, Sundqvist took a hit to the face by Janne Jalasvaara during a game and was forced to miss time to recover. Sundqvist said that he had "lost the feeling all over my face, still have no feeling on my nose and under my eye."

On 27 April 2015, following the completion of the 2014–15 SHL season, Sundqvist began his North American professional career after being reassigned to the Penguins' American Hockey League (AHL) affiliate, the Wilkes-Barre/Scranton Penguins. He played one game with the Penguins during their Calder Cup playoff run.

During the off-season, Sundqvist chose to remain in North America rather than return home to train. When reflecting on his decision, Sundqvist said "It's a big difference....I mean, last year I came here and I played between 6-10 games. Now I came here and haven't played any games, so I feel a big difference." Leading up to the 2015–16 season, Sundqvist was vying for the Penguins' fourth line centre position. Due to a hamstring injury, Sundqvist was unable to participate at the Penguins summer development camp but was healthy enough for their training camp. After attending the Penguins training camp, Sundqvist was shortly assigned to the Wilkes-Barre/Scranton Penguins before being recalled to the NHL prior to the 2015–16 opening night. The reason for the short-lived promotion was for salary relief for players on their injured reserve list. Upon returning to the Wilkes-Barre/Scranton Penguins in the AHL, Sundqvist played on the team's third line alongside Dominik Uher and Tom Kostopoulos. He was recalled to the NHL on 4 February 2016 and made his NHL debut the next day in a loss to the Tampa Bay Lightning. He scored his first career NHL goal in a 5–0 win over the New York Islanders on 2 April, scoring the first goal of the first period within the periods first 13 minutes. Sundqvist appeared in 18 games for the team during the regular season, as well as two postseason games, as the Penguins went on to win the Stanley Cup, defeating the San Jose Sharks in six games. Sundqvist did not play in the finals or in enough regular season games to get his name on the Stanley Cup; however, Pittsburgh honored him with a Stanley Cup ring and a day with the Cup.