Luck

Luck was believed to be, according to the Eleventh Doctor, "an intangible force that helps [ gamblers] win or lose". He deduced that Joe Buchanan had faith in luck from his dice cufflinks and horseshoe chain. The Minotaur fed on Joe's faith in luck, killing him. (TV: ) Luck was always fickle. (COMIC: )

"Jinxing" was when someone said something similar to "what could possibly go wrong". The Doctor was known to jinx himself with such statements, and immediately regret it. (TV:, , , )

The Seventh Doctor believed that luck was merely a "reductive misrepresentation of statistical prediction". (AUDIO: )

Bob Kreesus used a luck machine, which he had won gambling, on the thirteenth moon of the thirteenth planet in the Thirteenth Galaxy, in order to extract the good fortune of others, and make himself lucky. Unaware of Kresus' tampering, the Triskaidekaphobes believed themselves to be the unluckiest people in the galaxy, and feared the number 13 above all else.

When the Tenth Doctor and Rose Tyler visited on Friday 13 January 1213, they were struck by lightning, and rained on by cats. In the end, the Doctor defeated Bob Kreesus by destroying his machine. Having lost his luck, Kreesus slipped on a banana peel and fell off a cliff. (COMIC: )

A week after the Slitheen's failed attempt to plunge Earth into a nuclear war on 6-7 March 2006, Mickey Smith (TV:, , etc.) conducted an interview with Henry Van Statten. Van Statten told Mickey, that not unlike "daytrippers in the park", aliens that visited Earth sometimes scraps behind, and sometimes, things more interesting. And by his reckoning, times like that is when people like himself and Mickey got lucky. (PROSE: )

In 3005, luck could be used as a currency in Space Vegas. (PROSE: Time Traveller's Diary)