Most notably the make-up of the Klingons was modified for TMP. In TOS their foreheads were flat exactly like those of humans. The only distinguishing mark was their beards. In TMP and thereafter, however, the Klingons had ridges on their foreheads, to emphasize their being alien but probably also their martial nature.
It's never outright explained in canon, but given that the Klingons were conquered by the Hurq a long time ago and they were not apparently native to the Klingon homeworld, they would have needed warp drives to accomplish that. So presumably they stole the tech from the Hurq.
Attempting to replicate experiments by humans to create augmented soldiers, Klingon scientists used genetic material from human test subjects on their own people, which resulted in a viral pandemic which caused Klingons to develop human-like physical characteristics.
The changes are overall slight enough to be interpreted as a part of Worf's natural aging process. The make-up was not returned to the initial version of the first season for the flashbacks in TNG: "All Good Things" though.
Comparison of "Classic" and Discovery Klingons. All Klingons until 2154 have ridged foreheads. "Divergence" insinuates that Klingons would pass on the human traits including flat foreheads after the genetic treatment. For obvious reasons, all Klingons in TOS were affected by this genetic mutation still 110 years later.
Worf is an outsider to Klingon society, marked as different both by his positionally — adopted child of humans, member of Star Fleet — and by his unshakeable commitment to the values that Klingons espouse.
After season 1 of TNG wrapped production, Worf's facial prosthetics were either lost or stolen. This presented Michael Westmore, TNG's primary makeup designer, with an opportunity to improve the look of the character.
Worf has a son named Alexander with a half-human half-Klingon woman named K'Ehleyr, a character introduced in "The Emissary"; however, she is later killed in "Reunion", a "sequel" to that episode and part of the Worf story arc, leaving Worf as a single parent.
What happened to the actor that played Worf's son?
Actor and musician Jon Paul Steuer, who rose to fame as a child star playing Alexander Rozhenko in Star Trek, has died aged 33. The American, who appeared in the 1980s show Star Trek: Next Generation, was the first actor to play the character, who is the son of Worf and Ambassador K'Ehleyr.
Later in the series, she becomes involved with the Klingon character Worf, and they marry during the sixth season of the show. In the sixth-season finale Jadzia dies but the Dax symbiote survives, and in the seventh-season premiere returns with a new host Ezri Dax, played by Nicole de Boer.
The appearance of Klingons in Star Trek has evolved over time, with the original series using minimal makeup due to their tight budget. Later series introduced cranial ridges, and Discovery created a more alien look for the Klingons.
Star Trek: Lower Decks season 4, episode 9 reveals that Klingons have pink blood, a departure from their usual red blood. The choice to give Klingons pink blood was made in Star Trek VI: The Undiscovered Country to create an alien look and to avoid a higher film rating.
According to the reference book Star Trek: Star Charts, the Klingons first achieved warp capability in the Earth year 930 AD, i.e., during the time of Kahless.
Zefram Cochrane casts a long shadow on the entire Star Trek franchise. He was, after all, the man who helped launch humanity's journey to the stars by creating Earth's first Warp Drive, and the one who established First Contact with the Vulcans.
The Vedala were discovered around the middle of the 23rd century (in the year 2268 or 2269), and are recognized by the Federation as the oldest surviving race capable of interstellar space travel. The Vedala space was encountered in Quadrant 1 near the Gamma 7A star system of the Milky Way Galaxy.
The Romulans may have acquired warp drive through their alliance with the Klingons, and Picard would be right with his reference about the Romulans "a century ago" in "Insurrection".
Originally Answered: Did Worf have any children on Star Trek: The Next Generation? Yes he had a son named Alexander by a half human half Klingon woman who unfortunately was murdered by another Klingon and worf dueled him and killed him and got his revenge for the murder of his beloved mate.
Worf's correct last name is Rozhenko. It's his adopted name. Klingons don't have last names. They are referred to as [name], Son of [father's name], or House of [family's House name].
K'Ehleyr was a female Klingon-human hybrid introduced in the Star Trek: The Next Generation episode The Emissary, and the first wife of Worf. She was portrayed by Suzie Plakson, who also portrayed Doctor Selar, a Female Q, and an Andorian named Tarah in other Star Trek related productions.
Worf, the Klingon character in Star Trek: The Next Generation, was married twice. His first marriage was to K'Ehleyr, and his second was to Jadzia Dax in Star Trek: Deep Space Nine.
After years of shunning Klingon society, Alexander made a go of devoting himself to the Empire. He joined the Klingon Defense Force during the Dominion War, a choice he made without consulting his father.
Memory Alpha notes that there is no canonical maximum estimate for Klingon lifespans, but several Klingons are known to have exceed a century, and some may have made it past 150 (earyh) years. That makes them pretty comparable to 24th century humans.
The baldric didn't just show that Worf was Klingon. It was also an important celebration of Klingon heritage. While other baldrics might have been used to carry weapons, the Klingon ones were solely for honoring their family or house, something that was important to Worf.
By putting Worf in a yellow field jacket, the Picard writers' room and costume department imply that, following the Enterprise disaster, he's reverted to the Starfleet division in which he was always more comfortable.
