John G. Slaney (born February 7, 1972) is a Canadian former professional ice hockey defenceman. He is currently an assistant coach for the Tucson Roadrunners of the American Hockey League (AHL). He was formerly the assistant coach of the Portland Pirates of the AHL. Slaney was the first player born and raised in Newfoundland and Labrador to be a first-round NHL draft pick.

Slaney was born on February 7, 1972, in St. John's, Newfoundland and Labrador, Canada, to parents Joe and Helen. His father ran a barber shop while also raising Slaney and his four older siblings.

Slaney played midget hockey in St. John's, Newfoundland until 1988 when he was drafted into the Ontario Hockey League (OHL). As a 15-year-old, Slaney scored 41 goals and 69 assists through 61 games with the St. John's Capitals U18 AAA team. His scoring abilities garnered attention from scouts. He was the youngest player chosen for Team Atlantic at the U17 Esso Cup. Slaney was subsequently drafted in the first round of the 1988 OHL draft by the Cornwall Royals. Although it was later revealed that Slaney announced he would only play for the Royals. Slaney quickly earned praise from his Royals teammates and coaches at training camp, despite members of the media raising concerns about his size. Slaney began the 1988–89 season with two goals and six assists through his first seven games. He was also named the Royals' Star of the Game through his first two games with the team, despite them both being losses. By December, Slaney had improved to nine goals and 32 points in 33 games. He finished his rookie season with 16 goals and 43 assists for 59 points and was named the team's Most Sportmanlike Player and Scholastic Player of the Year.

He spent the offseason working with weights and began the Royals' 1989 training camp weighing 186 pounds. As a sophomore, he was expected to replace Mathieu Schneider as the team's best defenseman. In December, Slaney and teammate Owen Nolan tried out for Team Canada's junior team roster to compete at the 1989 World Junior Ice Hockey Championships, but were two of the final cuts. Slaney and Nolen were also selected to represent Team OHL in the annual OHL/QMJHL Challenge Cup. Upon rejoining the Royals, Slaney continued to lead all defencemen in scoring with 18 goals and 44 points. While the NHL Central Scouting Bureau originally ranked him as a second round pick in the 1990 NHL entry draft, Slaney climbed the ranks as the season progressed. He was ranked 23rd overall by the Scouting Bureau in February, but finished the season ranked seventh overall. Slaney was named the recipient of the 1990 Max Kaminsky Trophy as the best defenceman across the OHL at the end of his sophomore campaign. He was then awarded the CHL Defenceman of the Year Award, and selected for the First All-Star Team.

Slaney was eventually drafted 9th overall by the Washington Capitals in the first round of the NHL Entry Draft. While Keith Brown was the first NHL player from Newfoundland to be drafted, Slaney was the first born and raised Newfounder to be an NHL first-rounder. Slaney attended the Capitals 1990 training camp, where he impressed the team's coaching staff and was considered for their final roster. While he was eventually cut, the Capitals gave Slaney a tryout with their American Hockey League (AHL) affiliate, the Baltimore Skipjacks, during their preseason. He played one game with the team before returning to the Royals for the 1990–91 season. On November 30, 1990, Slaney signed a three-year $200,000 entry-level contract with the Capitals. Shortly after signing the contract, Slaney was one of 32 players named to Team Canada's national junior team tryout camp. Despite suffering from an ankle injury, Slaney attended the camp and made the final team.

Slaney scored the game-winning goal for Team Canada at the 1991 World Junior Ice Hockey Championships to lead the team to a gold medal. He injured his ankle while scoring the goal and had to leave the game, but returned to the ice for their post-win celebrations. Slaney returned to the Royals lineup following the tournament but suffered a lower-body injury in his second game back on January 6. While he was originally expected to miss two to three weeks with a charley horse, it became more serious than expected. It was later discovered that he had a blood clot in his right leg. Slaney underwent months of daily physiotherapy to recover, as he was originally unable to bend his leg beyond 20 degrees. He returned to the ice on February 28 after missing two months of game play, and quickly scored 10 points through his first four games. Despite missing significant time during the season, Slaney was named to the OHL's Second All-Star Team.

During the 1991 offseason, Slaney joined the Capitals fitness staff in Maryland and trained an intensive strength-building program under their guidance. He participated in the Capitals' 1991 training camp but was returned to the Royals for the 1991–92 season. Slaney played in two games for the Royals, recording five points, before suffering a shoulder injury in a game against the London Knights. The Royals struggled in his absence and won only one of eight games in November before he returned to the lineup at the end of the month. At the end of February, Slaney scored his 259th and 260th OHL point to pass Mike Stapleton for fourth place on the OHL's all-time scoring list. However, shortly thereafter, he suffered a hamstring injury and missed almost every game in March to recover. He returned to the Royals lineup for their final game of the regular season and played in their playoff series against the Ottawa 67's.

Once the Royals were eliminated from playoff contention, Slaney was reassigned to the Baltimore Skipjacks for the remainder of their 1991–92 season. He scored his first professional goal with the Skipjacks on March 28, 1992, in a 3–3 tie with the Hershey Bears.