These individuals are other characters in the novel and represent something other than themselves to Winston.
Tom Parsons--represents the perfect Party member. Tom is always active in the community hikes, and is the epitome of the Party. He is turned in by his daughter for thoughtcrime. If Tom Parsons isn't safe, no one is.
Syme--the man who is reponsible for developing the Newspeak Dictionary. He is very proud of his work, and talks widely about it. Winston decides early on the book that Syme will be vaporized since he is so outspoken about the progress of the language and his pride in his intellect. Syme is vaporized which justifies Winston's own intellect and ability to recognize those who are not good Party members.
Katherine--Winston's wife. She is wooden and unfeeling...especially during sex. She represents the good Party girl who follows the rules to the "T". She and Winston are separated since the marriage is a failure--they have failed to produce offspring for the Party.
The Trio--are the ones who defied the Party and lived to tell about it in the Chestnut Tree with their bottomless glasses of Victory Gin. They are innocent, as Winston has discovered, but no proof can be offered. They are killed in the name of the Party, and later in the book, Winston ends up in their shoes.