Joseph Woll
Current Leafs starter Joseph Woll won a gold medal with Team USA in the 2017 tournament as backup to Tyler Parsons.
Woll returned for the 2018 tournament, splitting starts with Dallas Stars netminder Jake Oettinger. The States earned a bronze medal that year.
Ilya Samsonov
Samsonov represented Team Russia twice at the World Juniors, in 2016 and 2017. After earning a silver medal in 2016 as the backup, Samsonov won another one in 2017, this time being a bronze. He also earned a spot on the tournament all-star team in 2017.
Martin Jones
Last but not least, Martin Jones played in the 2010 World Juniors, playing the role of backup for Team Canada.
While his playing time was limited, he did earn playing time in the gold medal game, coming in relief of starter Jake Allen.
Jones stopped every shot he faced in the latter part of the third period and the opening minutes of overtime before Team USA's John Carlson buried the OT winner.
Conclusion
In short, the Leafs have had quite a number of players represent their countries at the World Juniors over the years, with many walking away with numerous pieces of hardware.
The Toronto Maple Leafs look to continue to have strong WJC performances this year and in years to come.