"The Pool Guy" dedicated "In memory of our friend Rick Bolden"
???
"The Foundation" dedicated "In memory of our friend Marjorie Gross"
She wrote 5 or 6 episodes of Seinfeld. Died of breast cancer I believe.
"The Soul Mate" dedicated "In memory of our friend Victor Wayne Harris"
Victor was the assistant prop master for the series and he died in August following a stroke. (from the episode guide)
"The Butter Shave" dedicated "In memory of our friend Brandon Tartikoff"
He was the NBC exec. who fought for the continuation of "Seinfeld" through the first couple of lean years. He died of Hodgkins Disease in 1997
"The Burning" dedicated "In memory of our friend Lloyd Bridges"
A veteran actor who starred in one of TV's original action shows - Sea Hunt, had two sons who went on to acting, Beau and Jeff. He also stared in the classic film, High Noon (so beautifully parodied in The Race).- Lloyd played Mr. Mandelbaum, with his character based on fatherhood and toughness.
Marjorie Gross--I believe she was a Script Supervisor on the show. Check the end credits of an ep to be sure.
Brandon Tartikoff--one-time president of NBC TV and the guy responsible for putting Seinfeld on the schedule in the first place and sticking with it. He was forced out of NBC and later worked for New World TV and Paramount TV before his death from lymphoma.
Lloyd Bridges--played Izzy Mendelbaum in two episodes of the show, including the one dedicated to him (which was his last appearance in anything in his lifetime; an episode of the new Outer Limits in which he starred aired posthumously). Bridges started out years ago in character roles (i.e., in "High Noon" with Gary Cooper) in movies, but became one of the most enduring leading men in TV with his role in the '50s series Sea Hunt. As a result of the grueling roles he undertook, the guy kept himself in remarkably good shape--he was probably in better physical condition than many people half his age. Unfortunately, none of the other TV series he starred in over the years was as successful, but Bridges was an extremely visible performer for five decades in movies and TV. And like Leslie Nielsen, he proved to be a natural for comedy--he was also in "Airplane" and in the two "Hot Shots" movies.