"Get Smart" has Don Adams as Agent 86/Maxwell Smart, Barbara Feldon as Agent 99, and Ed Platt as the Chief. Those are the 3 *main* characters. Believe me there are more, but we'll get to that in a minute.
Basically 86 & 99 work for this top-secret government protection agency called "Control". They are employed by the US Government (they have a phone in the Chief's office that goes straight to the White House). Their rival organization is known as "Kaos".
Maxwell Smart (Agent 86) & his sidekick (Agent 99 - she has no real name) are sent on cases (or more like missions) to retrieve, disarm, uncover (or something along those lines) this or that. Max always manages to mess things up or something, it's great fun.
Kaos is run by Siegfried & his sidekick Shtarker. Kaos is Control's "bad guys".
HERE'S WHAT TVLAND.COM HAS TO SAY ABOUT "GET SMART":
In 1965 the cold war was made a little warmer and a lot funnier due in part to the efforts of an inept, underpaid, overzealous spy: Maxwell Smart, Agent 86. The hit comedy series Get Smart (1965-1970) is the creation of comic geniuses Buck Henry and Mel Brooks. Henry (The Graduate, Catch-22 and Saturday Night Live ) teamed with Brooks (Your Show of Shows, Blazing Saddles, Young Frankenstein) to create what has undoubtedly become one of the finest parody/satires of all time. The project seemed headed for success from the start: ABC had green lighted it based on the strength of the concept, and they had an actor already under contract to play Smart (Tom Poston.) Brooks was approached to write the pilot. As he was looking for a way to finance his new movie The Producers (now a Broadway musical), he agreed. Deemed "not funny", the initial script was rejected by ABC. Undaunted, the production team shopped the script around and NBC accepted it with one minor change. They wanted Don Adams in the title role. And so, an unlikely legend was born.
Set in Washington, D.C., the show features Agent 86 (Maxwell Smart), his boss (The Chief), Smart's partner and later wife (Agent 99) and a host of other agents both good and evil. Perhaps one of the most important elements of the show is the gadgetry created to help Smart in his quest to keep the free world free. On this show, anything including the kitchen sink can be a phone, a tape recorder, a camera or weapon. Looking for an Agent? Check under your seat cushion. Want a weapon? Try your finger-gun. Need to make a phone call? Open up that bologna sandwich. The show was painted in the broadest of strokes and played every moment for its own delightful reality.
In order to give the agents of CONTROL (not an acronym) a series of worthy opponents, KAOS (also not an acronym) was created. Smart and 99 battled the likes of Mr. Big, The Claw, and Siegfried.
On the home front, Max and 99 had a relationship that developed as the show ran and eventually they married. 99 soon gave birth to twins (a boy and a girl) and the Smart family (and the show) began to experience some growing pains.
Get Smart ran from 1965 through 1970 on both NBC and CBS. For one month in 1995 FOX attempted to bring the series back with some changes; Max as the Chief, 99 as a Congresswoman, and the Smart twins were now inexplicably only one child (Zach). Despite the lack of success experienced by the sequel, Get Smart remains a favorite by agents and civilians alike.