Several characters within the Star Trek franchise, primary and
secondary, often made crossover appearances between one live-action
series and another. This included appearances of established
characters on premiere episodes of new series, a few long-term
transfers from one series to another, and even crossovers between Trek
films and television. A few crossover appearances, such as that of
Spock on The Next Generation and the time-travel of the crew of Deep
Space Nine to the era of The Original Series were especially lauded by
both fans and critics.After the original series, a character from an
earlier series appeared in the premiere episode of each new series.
These were the appearances of Leonard McCoy in "Encounter at
Farpoint", the first episode of The Next Generation; that of Captain
Jean-Luc Picard in "Emissary", the first episode of Deep Space Nine;
Quark and Morn in "Caretaker", the premiere of Voyager; Zefram
Cochrane (from the original series episode "Metamorphosis" and the
film Star Trek: First Contact) in "Broken Bow", the premiere of
Enterprise; Sarek in "The Vulcan Hello", the first episode of
Discovery; and NOMAD (from the original series episode "The
Changeling") in "Second Contact", the premiere of Lower Decks.Two
long-term transitions were the transfer of Worf and Miles O'Brien from
permanent characters on The Next Generation to permanent characters on
Deep Space Nine. Worf stayed on The Next Generation until its
conclusion, then transferred from the start of season 4 of DS9. Chief
O'Brien had appeared in fifty episodes of The Next Generation, but
only gained opening credits billing on DS9, in which he appeared in
almost every episode of all seven seasons. While not seen as often as
Chief O'Brien, his wife Keiko O'Brien also transitioned as a series
regular guest star from The Next Generation to Deep Space Nine,
bringing their daughter Molly. Miles O'Brien reprised his Next
Generation role in that series' finale "All Good Things...".An
especially significant crossover is Spock's appearance on the two-part
Next Generation episode "Unification". Spock meets Data and they
exchange opinions on the relative value of logic and emotion, and
share mutual impressions of Next Generation's Captain Picard (who for
Spock is a model of logical behavior, and for Data is a model of what
it means to be human). Critics such as Ina Rae Hark have noted this
encounter between two non-human characters summarizes their
contrasting attitudes to humanity, Data embodying Spock's ideal of
pure logic, while Data aspires to be more human. Star Trek crossovers Biography, NetWorth, Height, Age, Weight, Family, Married, Son, Daughter