Now that DC has "merged" its various versions of Superman and Lois Lane, the publisher has officially brought into continuity the son of Superman, Jonathan Kent.
This isn't the first time readers have seen stories about a son of Superman - from DC's many "Elseworlds" stories and future iterations to the controversial film version in Superman Returns - but Jonathan Samuel Kent is the first time Lois and Clark's child has existed in present-day continuity, fully part of the current DC timeline.
Jonathan Samuel Kent
Perhaps encouraged by the popularity of Damian Wayne, the son of Batman who debuted in his modern version in 2006, DC first introduced Jonathan Samuel Kent during their Convergence storyline of 2015, an event that explored characters from alternate continuities.
Convergence was published roughly four years after DC launched its "New 52" initiative, a reboot that dumped a lot of previous continuity - characters and concepts that readers missed. Included in the reboot was the elimination of Lois Lane and Clark Kent's marriage from continuity, with DC instead establishing Clark Kent as a young, single and sometimes brash hero.
During the Convergence spin-off miniseries Convergence: Superman by Dan Jurgens and Lee Weeks, readers were shown that the previous, older, married Superman had actually lived on after the reboot. Because he was grabbed by Brainiac before his world died, he and Lois continued their lives and, eventually, had a baby together.
Through a series of unusual events (including actually preventing DC's Crisis on Infinite Earths from ever happening), married Clark and Lois ended up on the main DCU Earth with their son Jonathan Samuel Kent.
Alternate Jon Kents
There have been several other Jonathan Kents in DC stories of the past, although most of them have been outside regular DC continuity.
In 1986, DC published an imaginary story titled "Whatever Happened to the Man of Tomorrow?" by Alan Moore and Curt Swan. Meant to celebrate the end of the Silver Age Superman, the story showed how Superman got rid of his powers and settled down with Lois under the alias of Jordan Eliott. The couple had one child together, whom they named Jonathan (and who, by the end of the story, showed signs of superpowers).
In 1999, the Elseworlds story "Son of Superman" imagined a world where Superman had been missing for some time, but his son Jon Kent was raised by Lois without knowing that his father Clark Kent was secretly Superman. When he begins to develop superpowers, Lois tells him about his father, and the boy decides to rescue Superman.
In the Kingdom Come universe - set in a future where superheroes are in conflict - Superman eventually ended up with Wonder Woman. Their son, Jonathan Kent, takes the name Hyperman and becomes the guardian of Hypertime.
Jon Lane Kent
But there's also a scary, evil version of Jon Kent that came into continuity pre-"Rebirth." As part of the origin of "New 52" Kon-El Superboy, readers were introduced to a villainous version of Jon.
This version of Jon was the son of Lois and Clark in an alternate future, and actually died because his hybrid human-Kryptonian physiology was unstable. But a time-traveling villain named Harvest kidnapped and revived him, then trained him to hunt and kill metahumans.
Jon's destiny was linked to Kon-El because, as part of the rebooted origin stories in the "New 52," Harvest created Kon-El as a clone of Jon Lane Kent. For awhile, this evil version of Jon Kent even replaced Kon-El in current continuity.
Eventually, Jon Kent sacrificed himself and returned Kon-El to the status of current Superboy.
Now that "Superman Reborn" has combined the "essence" of the "New 52" Superman with the "essence" of his predecessor, DC has a new, young-but-married-with-a-kid Superman and Lois Lane Kent.
That means Superman's son, Jonathan Samuel Kent, is officially part of current DC continuity - no longer an immigrant from another continuity. He was born on the main DC Earth, was raised there with his father as Superman, and now resides there as part of the superhero community, carrying the mantle of Superboy in both Super Sons and Action Comics.