This Sunday marks the end of an era with the conclusion of AMC’s hit drama "Mad Men". Through the show’s seven seasons, we’ve traveled from 1960 to 1970 with the smoking, drinking, adulterous employees of the Sterling Cooper Draper Pryce advertising agency.

In a few days we will see how the show actually ends, but that hasn’t kept the Internet from guessing how the show will close. Below are the craziest, most intriguing, and most popular theories on how the show will end. WARNING: MAJOR SPOILERS AHEAD!

Don is D.B. Cooper

This theory turns Don Draper, a man who has already reinvented his identity once (remember, Don Draper is actually Dick Whitman), into famous criminal D.B. Cooper.

Cooper hijacked a Boeing 727 in 1971 after buying a ticket under the name Dan Cooper (D.B. Cooper is a name used by the media, his true identity is unknown). The man sat in the back of the plane and had a drink (sounds like Don). Halfway through the flight, he calmly told a flight attendant he was carrying a bomb and began collecting over $200,000 in cash and jewelry from the plane’s passengers. Cooper then parachuted out of the plane and was never found.

Don becomes the man from the opening credits

This theory has been popular since season 1. Many wonder if Don will become the faceless man in the show's opening credits, plunging to his death past popular advertisements. The show has alluded to loose windows and suicide in prior episodes, only adding to this speculation. Some even think Pete Campbell will become the man from the opening credits, but it's more likely Pete's future lies with the next theory.

Pete and Don die in the Wichita State plane crash

In the show's penultimate episode, Pete Campbell accepted a job with Learjet in Wichita and is guaranteed the use of a private plane. Don is also in Kansas on his seemingly endless road trip. Could they soon be victims of the Wichita State University plane crash? Many think so.

On October 2, 1970, a private jet flying the WSU football team to a game in Utah crashed in Colorado, killing 31 of the 40 people onboard. Speculation is rife that Don and Pete will be on the plane, and possibly Duck Phillips too.

Don teaches the world to sing

As of last Sunday’s episode, Don is a man most likely out of a job due to his spontaneous road trip that has yet to end. But what if he does return to New York City and McCann Erickson, perhaps after receiving news of Betty’s lung cancer? It would take an amazing pitch to save his job, his family, and the millions he is owed from the SCDP merger.

What pitch could save Don? The most iconic television commercial of the 1970s: "I'd Like to Buy the World a Coke." Coca-Cola has been mentioned often this season and Don physically repaired a Coke machine in the prior episode. Could he repair Coca-Cola's image too?

The show is Ken Cosgrove’s memoirs

Ken Cosgrove is often seen as a minor character on the show, popping up when convenient to move the storyline along or to make it more interesting (remember when he was shot in the eye by a client?). But Ken's longing to write a novel has been a consistent thread in the show since season 1. When we last saw Ken, he was leaving the advertising world to "finally write his novel." Could "Mad Men" be that novel, a slightly-fictional tell-all of the 1960s advertising world?

Tune in to the "Mad Men" finale this Sunday at 10p.m. on AMC to find out.