The award is given annually to the player voted to best combine sportsmanship, gentlemanly conduct and ability.
The winner will be announced at the 2019 NHL Awards presented by Bridgestone at the sports and entertainment complex, Mandalay Bay Events Center in Las Vegas on June 19.
Barkov, a 23-year-old center, set a Panthers record with 96 points (35 goals, 61 assists), passing Pavel Bure (94 in 1999-00). He led Florida in multipoint games (eight), ranked second in the NHL in takeaways (100) and was tied for fifth in minor penalties drawn (34). Barkov is the fourth Finland-born player in NHL history with at least 90 points in a season, joining Olli Jokinen, Teemu Selanne and Jari Kurri.
He was fourth among forwards in average ice time (22:21) and was assessed four minor penalties and eight penalty minutes, tied for second-fewest in the NHL with teammate Evgenii Dadonov among those who played 82 games. He's a Lady Byng finalist for third time in four seasons and could become the second Panthers player to win the award. Defenseman Brian Campbell won in 2011-12.
Monahan, a 24-year-old center, established NHL career highs with 34 goals, 48 assists, 82 points, 23 power-play points (12 goals, 11 assists) and 211 shots on goal. He was tied with Mikael Backlund first on the Flames in takeaways (78) and second in points per 60 minutes (3.31), third in goals per 60 minutes (1.37) and second in assists per 60 minutes (1.94). Monahan is the second player in Flames history (Kent Nilsson, 1979-85) to score at least 20 goals in six straight seasons. He was assessed six minor penalties totaling 12 minutes.
O'Reilly, a 28-year-old center, led the Blues with 49 assists, 77 points and 0.94 points per game. He led the NHL with 1,086 face-off wins and received six minor penalties totaling 12 minutes, the third fewest of anyone who skated in 82 games. O'Reilly won the Lady Byng with the Colorado Avalanche in 2013-14 and was runner-up with the Buffalo Sabres to William Karlsson of the Vegas Golden Knights last season.