Endings are notoriously difficult to get right -- especially on a long-running TV show where so many people have invested so much for so long.
Here are some of the most talked about:
Twin Peaks (June 1991) -- Who killed Laura Palmer? This is the question that drove "Peaksmania", and after the network, spooked by declining ratings, pushed David Lynch to identify the killer halfway through the second season, public interest plummeted.
The show limped on for a further six episodes, and Lynch, having taken a back seat for most of the second season, brought his distinctive style to the otherwise anti-climactic final episode.
The Sopranos (June 2007) -- Described by the Washington Post as "the greatest double take by the audience in the history of American television", but by the New York Times as "a prank", HBO's mobster drama The Sopranos bowed out after eight years with the screen suddenly going blank after an incredibly tense build-up that suggested Tony Soprano (James Gandolfini) was about to be rubbed out.
Series creator David Chase hailed the ending as a "revolution", but some fans and critics felt cheated.
Ashes to Ashes (May 2010) -- The papers had few good words for last week's send off to time-travelling cop shows Life on Mars and Ashes to Ashes -- "self-indulgent nonsense" (Observer) and "unsatisfactory" (Sunday Times).
DCI Gene Hunt (Philip Glenister), it seemed, was the ghost of a young PC murdered on duty who now acted as a sort of guardian angel to other dead cops, including Alex Drake, Shaz, Chris and Ray.
M*A*S*H (February 1983) -- "Goodbye, Farewell and Amen" was the title of the 251st and final episode of the Korean war comedy, which went on to become the most-watched television broadcast in American history.
The two-and-a-half-hour special was intended to show the war's effect on the regular characters after the ceasefire, and the TV critic for Onion AV club website, looking back in 2007, wrote that, "few TV series have done a better job of closing up shop. The final half-hour is beautifully bittersweet".
Seinfeld (May 1998) -- Frank Sinatra died on the same night as the two-part Seinfeld finale screened, but probably not from laughing.
In fact, the ambulance taking Ol' Blue Eyes to hospital made good time through the usually clogged Los Angeles traffic because most people were at home watching the episodes in which the main characters nearly die in a plane crash, before being convicted under Massachusetts' "Good Samaritan laws".