Inspector Gadget would never have sprang into being without the existence of Maxwell Smart.
Get Smart, a brilliant satire of the spy genre, lasted 5 seasons (1965-70), the first 4 on NBC, which foolishly dumped it, along with another iconic series, Star Trek, after the 1968-9 season, only for CBS to pick it up for the fifth & final season. Maxwell Smart, aka CONTROL Agent 86, was a blend of Peter Sellers' Inspector Clouseau ("The Pink Panther") and James Bond. Don Adams played Smart as a confident, but often oblivious, agent who seemed to be a little slow on the uptake until the clues came together, a formula he'd replicate for Inspector Gadget 13 years after Smart ended its first run.
While Bond had Miss Moneypenny pining for him, Smart had a strikingly gorgeous partner in Agent 99 (Barbara Feldon), who made sure Smart stayed on the trail of the bad guys, and ultimately captured his heart as well, as the two agents were married in season 4. The Chief (Edward Platt) could probably empathize with Clouseau's boss, since Smart could be irritating with his mental lapses. Fortunately, he didn't go insane.
On the other side was KAOS, whose leader, Mr. Big (Michael Dunn, The Wild, Wild West) was seemingly killed off early on. Once Dunn was cast as Dr. Loveless on West, he wasn't brought back to bedevil Smart a 2nd time. From that point, KAOS' point man was Conrad Siegfried (Bernie Kopell), who was about as over the top as you could get. Despite being mortal foes, Siegfried and Smart had a mutual respect, which became part of a plotline later in the series. Because Siegfried only appeared a few times a year, Kopell had time to work on other series, such as That Girl and The Doris Day Show.
NBC must've felt the well had run dry after the 4th season, since Smart & 99 had wed. However, the producers had other ideas, and the Smarts welcomed twins in season 5.
Here's the intro everyone remembers:
Two years after Smart ended, Adams returned to NBC with The Partners, and brought along his cousin, Robert Karvelas (Larrabee on Smart), as a serial confessor. Unfortunately, Partners lasted 1 season. Following a 1980 feature film, "The Return of Maxwell Smart", aka "The Nude Bomb", it would be 15 years before Smart would be in another series. Fox picked up the baton and took a chance on Get Smart, Again, which saw at least one of Max & 99's kids join the family business. Ed Platt had passed on in the interim, and would be the only regular from the original series missing from the remake. We'll look at that another time.