The owners of the 76ers announced Monday they have purchased a controlling stake in two e-sports teams, Dignitas and Apex, becoming the first North American sports franchise to own e-sports teams.

E-sports are video-game competitions. They have existed on consoles and online for decades, but the popularity has grown to where fans fill arenas to watch on giant screens as professional players compete.

Dignitas has existed since 2003, and is one of the most established e-sports organizations. It competes in many games, including League of Legends, Heroes of the Storm, and Smite. Apex is newer, but brings a guaranteed spot in the League of Legends Championship Series - one of the top e-sports competitions in the world.

The two teams will be combined and will operate under the Dignitas brand.

Terms of the deal were not disclosed, but the report said well-established franchises are valued at between $5 million and $15 million.

Although the 76ers are the first North American major pro sports team to operate an e-sports franchise, they aren't the world's first major sports team to do so. One of Germany's biggest soccer clubs, Schalke 04, owns a team that competes in the European League of Legends Challenger Series. Another major e-sports team, NRG, counts ex-NBA star Shaquille O'Neal and former Phillies shortstop Jimmy Rollins among its investors.

"There's no denying the fact that e-sports presents corporate America with a way to reach millennials in a way stick-and-ball sports just isn't," 76ers CEO Scott O'Neil told ESPN.

O'Neil wasn't just talking about gamers, by the way. The top e-sports competitions in the world have become major spectator events, drawing big crowds to NBA-sized arenas and millions of worldwide viewers to online broadcasts.

Follow and contact 76ers beat writer Keith Pompey on Twitter on Twitter and on Instagram at PompeyOnSixers.

Staff writer Jonathan Tannenwald contributed to this report.