There were 13 people at the Last Supper.
It's said that Judas Iscariot and the one who betrayed Jesus - was the 13th man to take his place at the table.
Similarly, there’s a Norse legend that has 12 gods sitting down to a banquet when the 13th (uninvited) god, Loki, shows up
Traditionally, there used to be 13 steps leading up the gallows.
There's also a legend that a hangman's noose traditionally contained 13 turns, but it's actually more like eight.
Apollo 13 is the only unsuccessful moon mission (intended to get men on the moon, anyway) thus far.
An oxygen tank exploded and the survival of the astronauts on board was pretty touch-and-go for several days, but they did all come home safely in the end (but you already knew that).