|Born|| December 8, 1992 |
|Height||6 ft 1 in (1.85 m)|
|Weight||189 lb (86 kg; 13 st 7 lb)|
| NHL team|
| Dallas Stars|
|NHL Draft|| 79th overall, 2013|
Detroit Red Wings
During the 2009–10 season, Mattias played his first full season with AIK in Stockholm in Sweden's top division after joining the club mid-season from the lower division club SDE HF the previous year.
He played for AIK's U20 and U18 teams; appearing in 17 games, including four playoff games, with the U20 team and playing in 34 U18 contests, including one playoff game.
Mattias recorded four goals and eight assists in U20 play and had 13 goals with 22 assists for AIK's U18 team.
During the 2010-11 season, Mattias skated for AIK Stockholm's U20 team, playing in 40 Super Elit league games. He recorded 11 goals and 17 assists. AIK finished sixth in the Super Elit league's North Division.
During the 2011–12 season, Mattias made his pro debut in Sweden's Elitserien, appearing in 18 games for AIK Stockholm, and was the team captain for the club's U20 team. He had no points in limited ice time in Elitserien play.
He also appeared in three playoff games with AIK with no points or penalties. In 40 games for the club's U20 team, he was the team's leading scorer with 23 goals and 38 assists.
AIK finished fourth in the U20 standings but lost to Färjestads in a first round playoff series.
In his second year of draft eligibility, Mattias was ranked 98th amongst European skaters in Central Scouting's final rankings but was not selected in the 2012 NHL Entry Draft.
During the 2012–13 season, Mattias had an impressive first full season in Sweden's Elitserien, finishing as AIK's second-leading scorer, behind Broc Little. In 55 games Janmark recorded 14 goals and 17 assists.
AIK missed the Elitserien playoffs, finishing six points behind eighth-place Brynäs for the final spot.
On April 15, 2014, at the conclusion of his season with AIK, Mattias was assigned by the Red Wings to the Grand Rapids Griffins on an amateur try-out conract. He made his AHL debut on April 18th, in a game against the Lake Erie Monsters.
For the following 2014–15 season, Mattias opted to remain in the SHL, signing a one-year contract with Frölunda HC on June 3, 2014.
At the conclusion of the season, having scored 36 points in 55 games, Mattias ended his SHL tenure in signing a two-year entry-level contract with the Dallas Stars on April 24, 2015. He was immediately assigned to join the Stars AHL affiliate's playoff run, in Texas.
On October 8, 2015, Mattias made his NHL debut, netting his first career goal on his first shot on his first shift, 99 seconds into the game.
|2013–14||Grand Rapids Griffins||AHL||2||0||0||0||2||6||0||1||1||0|