This month the German SF-series Perry Rhodan celebrates it's 50th birthday, half a century old and still going strong - First issue 09/08/1961 . That probably makes it the longest running continual series in history. Although they managed in that time only one movie adaptation, which then failed miserable at the box-office, we don't let that keep us from congratulating!
Live long and prosp... err, wrong series. Best of luck for the next fifty!
"When someone doesn't show up, the people who wait sometimes tell stories about what might have happened and come to half believe the desertion, the abduction, the accident. Worry is a way to pretend that you have knowledge or control over what you don't--and it surprises me, even in myself, how much we prefer ugly scenarios to the pure unknown. Perhaps fantasy is what you fill up maps with rather than saying that they too contain the unknown."— Rebecca Solnit