Initials of Lyndon Baines Johnson, 36th President of the United States.

In 1968, as part of a plot to gain access to CONTROL's files, KAOS agents tap into their hotline to the White House and, imitating the President's voice, promote Maxwell Smart to the position of Chief.

At one stage, believing that he has been conversing with the real president, Max refers to him as "L", claiming that they are "on a first name basis now".

[Episode #84: "The Hot Line".]