Bsrgvty

In T. Pratchett's Discworld series, Death's motto is "Non Timetis Messor", meant to be a translation of "Don't Fear the Reaper". But in other books he uses "Timetere", and I am unsure of which would be correct, if either of these. The imperative form of "Fear" is the root of the whole issue here.
This phrase is probably going to be tattooed on my shoulder one day, so I'd quite like to have the correct translation ^^

Thanks in advance!

Neither is correct, and timetere isn't a real Latin word. A correct translation depends somewhat on whether the command is directed at one person (e.g., you, the bearer of the tattoo) or the world at large (e.g., those who see the tattoo).

For the former case (audience = one person), you could say Noli messorem timere or Ne messorem timueris. Ne messorem timeas is also OK and would tend to make the expression somewhat impersonal ('One must not fear the fear'). In all three, messorem could be moved so that it's the last word instead of the second word.

For the latter case (audience = more than one person), the corresponding translations are Nolite messorem timere, Ne messorem timueritis, and Ne messorem timeatis.

For each audience, the three versions are interchangeable; so you can go for the version that sounds – or, since a tattoo will be involved, looks – the best to you.

If you wish to avoid thinking about intended audience, you can instead use a passive expression that means 'The reaper is not to be/must not be feared': Messor non timendus est. In Latin, this too has the force of a command. For the sake of brevity, you can omit est. You can also replace non with other negators, such as minime ('not at all'), haud, or nullo modo ('by no means'), if you think they will sound (or look) better.

In all these instances, messor is a solid, literal translation of 'reaper.' If you want something more evocative, perhaps, you could try falciferum instead of messorem in the first set of translations, and falcifer instead of messor in the second. This word means 'the scythe-bearing one.'

When (Sir) Terry Pratchett was knighted, he chose this phrase as his heraldic motto. The official translation in that context is Noli Timere Messorem.

This isn't the most natural word order (which would be noli messorem timere), but the meaning is the same: a command to a single person, "do not fear the reaper".

Death's motto makes me recall the Centurion scene in Monty Python's The Life of Brian. Non timetis in fact "don't fear", but rather "(you all) don't fear" in the indicative, rather than the imperative. Also "Messor" is in the nominative rather than the accusative. I expect that Mr Pratchett either deliberately mangled the phrase to be facetious or he simply didn't care about being gramatically correct. In any case, that's what I would expect Altavista Translation would spit out when given the English phrase to translate, circa 1995.

The usual forms which serve as a negative imperative in Latin: the first is noli/nolite + infinitive or ne + present subjunctive. In both cases it will take a complement in the accusative. So:

Nolite messorem timere

or

Ne messorem timeatis