The 84-year-old actor who played "Scotty" decided to retire after being diagnosed with Alzheimer's disease (search) several months ago. He blew kisses to a crowd of Trekkie faithful gathered at the Sunday finale of a two-day tribute held at the Renaissance Hollywood Hotel.
Doohan, who also has Parkinson's disease and diabetes, mingled with fans and spoke at a news conference between Scotty impersonation contests and a panel discussion titled "The Influence of Scotty on Society."
"He wanted to say goodbye to his fans," said Dave Mendel, of Berryville, Va., who dressed in full Klingon battle armor. "How could you not show up for that?"
The event's proceeds will benefit an Alzheimer's research foundation.
Doohan, whose character was Chief Engineer Montgomery Scott of "Beam me up, Scotty" fame, has won the goodwill of fans who say he always took time to sign autographs and talk trivia.
Many planned to attend Tuesday's ceremony honoring Doohan with a star on the Hollywood Walk of Fame. The event was expected to be his final public appearance.
"We're just very proud to honor Dad with this star," said his son, Chris Doohan. "A lot of `Star Trek' fans helped us out with this."