Agent 99 was the beautiful, mysterious spy who often had to rescue bumbling Agent 86, Maxwell Smart (Don Adams), her fellow agent and later husband in the wacky spy spoof.
A multi-talented woman of the world, 99 spoke Chinese, German, and French, and was a skillful violinist and harp player, as well as an accomplished dancer.
Agent 99's real name was never revealed --during one episode she said her name was "Susan Hilton," but when Max called her Susan she told him it was a fake name.
The character was also a former fashion model and could have had any man she wanted, but she was obsessed with Max. Barbara told an interviewer that 99 was "totally preoccupied with adoring Max. It was all Max all the time."
She was smarter, more ingenious and more competent than Agent 86. Manytimes she conceived ideas and made Max believe that he'd thought of them. Barbara played her role of the straight man to Max's comedic blundering to perfection, rolling her eyes when he did something stupid.