Star Trek: Picard seasons 1 and 2 included some major deaths of Star Trek legacy characters. Picard season 1 killed off Hugh (Jonathan Del Arco), the former Borg who at least got a reunion hug with Admiral Picard before he died. Dr. Bruce Maddox (John Ales), who built a new race of synthetics from the positronic neuron of the late Lt. Commander Data (Brent Spiner), also died in Picard season 1, along with Icheb (Casey King), one of Seven of Nine's (Jeri Ryan) Borg 'children' from Star Trek: Voyager.
Q (John de Lancie) died at the end of Star Trek: Picard season 2, although the reports of his demise were exaggerated since the omnipotent being came back at the end of Star Trek: Picard season 3. Although Captain Rachel Garrett (Tricia O'Neill) of the USS Enterprise-C died decades prior, Vadic added insult to injury by destroying her Red Lady statue on M'Talas Prime. Elsewhere in Star Trek: Picard season 3, the following familiar faces from Star Trek: The Next Generation returned, but not for long.
4Commander Ro Laren
Played By Michelle Forbes
Ro Laren died heroically to protect Admiral Picard and the USS Titan-A from the USS Intrepid, which was under Changeling control and about to fire on the Titan. Changeling agents planted a bomb on Commander Ro's shuttle, but Laren piloted it into the Intrepid's nacelle, causing enough damage to allow the Titan to escape.
Commander Ro Laren also revealed herself as Captain Worf's (Michael Dorn) handler from Starfleet Intelligence.
Although Star Trek: Picard season 3 showrunner intended for the finale to include a scene where Commander Ro Laren was alive and imprisoned by the Changelings, it wasn't filmed. Therefore, Ro Laren's death in Star Trek: Picard season 3 remains canon. Still, Ro redeemed herself in Admiral Picard's eyes, and Star Trek: Picard season 3 closed the circle and concluded Ro's open-ended story from Star Trek: The Next Generation.
3Lore
Played By Brent Spiner
When Commodore Geordi La Forge (LeVar Burton) lowered the partition in Data's brain, Lore attempted a hostile takeover of their shared Soong hybrid body. However, Data tricked Lore by using his memories of his former life on the USS Enterprise-D to override Lore and delete him, giving Data complete control over their synthetic form. Lore has plagued Data since Star Trek: The Next Generation season 1, and remained a threat long after his android form was destroyed. Presumably, Lore is now gone for good.
2Admiral Elizabeth Shelby
Played By Elizabeth Dennehy
Commander Elizabeth Shelby was a memorable force in Star Trek: The Next Generation's classic two-parter, "The Best of Both Worlds." The ambitious and career-minded Shelby became First Officer to Acting Captain Will Riker (Jonathan Frakes) after Captain Picard was assimilated into Locutus of Borg. After leaving the USS Enterprise-D, Shelby headed up Starfleet's Borg task force. In Star Trek: Lower Decks, Captain Shelby was seen at a Starfleet gala event.
1The Borg and Borg Queen
Played By Alice Krige & Jane Edwina Seymour
Another Borg Queen and a benevolent Borg Collective still exist, as a hybrid comprised of Dr. Agnes Jurati (Allison Pill) and the Borg Queen (Annie Wersching) from the Confederation of Earth alternate timeline, entered Star Trek's Prime Timeline and were granted probationary Federation membership by Admiral Picard.
In Star Trek: Picard season 3, the Borg Queen enacted a long-range plan to assimilate Admiral Picard's son, Jack Crusher (Ed Speleers), who was born with organic Borg DNA passed to him by Picard from when he was Locutus. Turned into Vox of Borg, Jack emitted the signal that led to the mass assimilation of every Starfleet Officer under the age of 25, creating a new version of the Borg Collective. However, the Borg Queen and the remains of her Collective failed in their bid to be reborn. The Borg Queen's death in Star Trek: Picard season 3 saw Admiral Picard defeat his greatest enemy, at last.