I asked Gemini for a list of ALL the TOS cast members who are still living and it gave a bunch of the more famous stars:

• Clint Howard (age 67): Famously played the alien child Balok (voiced by Walker Edmiston) in the Season 1 episode "The Corbomite Maneuver". [1]
• Gary Lockwood (age 89): Played Lt. Commander Gary Mitchell, Captain Kirk's friend who gains god-like powers in the show's second pilot episode, "Where No Man Has Gone Before". [1, 2]
• Barbara Babcock (age 89): Played Mea 3 in "A Taste of Armageddon" and provided the uncredited, elegant voices for the alien computers/entities Trelane's Mother ("The Squire of Gothos") and the Beta 5 computer ("Assignment: Earth"). [1]
• Sandra Lee Gimpel (age 86): Played the distinctively large-brained Talosian alien creature in the original pilot episode, "The Cage". [1, 2]
• Sean Kenney (age 82): Played Lieutenant DePaul in two episodes, but is most famous among fans for physically portraying the severely disabled, wheelchair-bound version of Captain Christopher Pike in "The Menagerie". [1]
• Anthony Call (age 86): Played the hot-headed navigator Lt. Dave Bailey in "The Corbomite Maneuver". [1]
• Andrea Dromm (age 85): Played Yeoman Smith in "Where No Man Has Gone Before". [1]
• David L. Ross (age 87): Played Lieutenant Galloway, a recurring security guard/redshirt who holds the rare distinction of being killed by an alien in one episode ("The Omega Glory") and mysteriously appearing alive again in another. [1]

Clint Howard, Gary Lockwood (also of 2001 fame!) and Anthony Call I remember well. The others not so much.