WARNING: The following article contains spoilers for "Nevermore," the season finale of Young Justice: Outsiders, streaming now on DC Universe.

With Season 3 of Young Justice in the books, it's time to look to what the future holds for the animated series. Many of the season's subplots came to a satisfying conclusion in the final three episodes, released this week on DC Universe, which means the creators had to introduce something to entice fans to return for the already-in-production Season 4.

Young Justice has never shied away from bringing some of DC's most popular heroes to the small screen, but the next group of characters teased to debut in Season 4 may have the biggest fan base of them all.

RELATED: Young Justice's Blast From the Past Reunites Them With [SPOILER]

After a short recap of recent events -- the metahuman center Taos welcoming all of the rescued kids involved in the metahuman-trafficking ring in outer space, Forager revealing his identity to his classmates at Happy Harbor High School, Geo-Force ruling as the new king of Markovia and Cyborg stopping a kid from being bullied -- we see the majority of The Team and Outsiders celebrating at Bibbo's diner.

The camera follows a blonde waitress as she moves among the tables and booths to serve the heroes. Her final stop brings her to Superboy and Miss Martian, where she pours the couple another coffee. Before the scene goes to black, the camera zooms in to reveal she is wearing a Legion of Super-Heroes flight ring on her right hand.

This scene basically confirms the Legion of Super-Heroes will debut in the next season of Young Justice. Hailing from the 31st century, the Legion of Super-Heroes is a coalition of teenagers and young adults from various planets in the DC Universe, who come together to form their own super-team. The Man of Steel -- known as Superboy at the time -- would go on to join the Legion's ranks in their future, fighting alongside the same heroes he helped inspire.

Although Young Justice Season 4 will mark their first appearance on the season, it's won't be the first time the fan-favorite team has been adapted for the small screen. Superman: The Animated Series introduced viewers to Cosmic Boy, Chameleon Boy and Saturn Girl, another version of the Legion guest-starred on Justice League Unlimited, and the Legion of Super-Heroes also headlined their own animated series in 2006. Earlier this year, Warner Bros. Animation released an animated movie titled Justice League vs. the Fatal Five that teamed the Justice League with the Legion against the latter's arch-rivals.

RELATED: Young Justice Turns DC's Greatest Heroes Into Darkseid's Newest Weapons

The identity of the Legionnaire working in Bibbo's diner remains a mystery for now, but the long blonde hair may give us a clue. The most likely suspect is Saturn Girl, as she was a founding member of the team. It also raises the questions of what brings the Legionnaire to the present day, and why she is hiding her identity. Superboy made some major changes to his status quo this season, outing himself as a public hero and officially joining the Outsiders. It's quite possible those choices are only the beginning of his rise as a superhero, leading to him being the inspiration for the Legion instead of his brother, Superman.

Coincidentally, the Legion of Super-Heroes is about to make a big splash this week in the comics as well. The Legion returns to the DCU in Superman #14 to recruit Superman's son, Jon Kent, which sets the stage for the two-part Legion of Super-Heroes: Millenium miniseries in September, followed by the launch of a new ongoing series in November.

Young Justice: Outsiders is currently streaming on DC Universe.

KEEP READING: Young Justice's First Post-Credits Scene Name-Drops a Major DC Weapon