Star Trek: The Next Generation introduced a son for Lt. Commander Worf.
Alexander, who was the son of Worf and the half-Klingon–half-human Ambassador K’Ehleyr (Suzie Plakson), was introduced in the fourth season of Star Trek: The Next Generation when K’Ehleyr returned to the Enterprise to help Captain Picard arbitrate the selection of the new Klingon leader. Worf was surprised to learn that Alexander was his son, but because of his dishonor, he could not claim him as his child. But the episode ended with K’Ehleyr’s death and Worf becoming Alexander’s sole parent, something which the series ultimately considered a mistake.
Only present in eight episodes of The Next Generation, Alexander was never really given a storyline other than serving to annoy Worf and point out he wasn’t father material at that point. The producers of TNG, according to Whatculture, weren’t really interested in pursuing a story with the young boy. And nobody seemed to know what to do with him, something writer Joe Menosky hoped to remedy when he wrote the premise of Star Trek: Deep Space Nine’s “Time’s Orphan.”
Alexander disappeared from Star Trek: The Next Generation after a few episodes.
Menosky, in writing “Time’s Orphan” intended to kill off Alexander, but producer Michael Pillar wasn’t onboard with the boy’s death so that episode was changed to focus on Molly O’Brien. Alexander did show up on Star Trek: Deep Space Nine to clash with his father and to further show the audience that Worf hadn’t been there for his son.
After his time at Deep Space Nine, Alexander returned in three novels that continued the series before making his final appearance in Star Trek Online when he sacrifices himself to save Worf from being killed. With Worf (Michael Dorn) returning to Star Trek: Picard next season, I do wonder if his son will be mentioned at all or if he will simply be ignored like he was after leaving Deep Space Nine.