Someone who constantly tells lies can be labeled as a liar.

Is there a word that describes someone as a person that constantly uses ruses(sp?)?

I found that in the definition, if you go to the old english get the following: 1375-1425; late Middle English (noun use of obsolete rusen to detour) < Middle French, derivative of ruser to retreat.

So a liar is someone who lies, a cheater is someone who cheats, what do you call someone who uses the ruse as a common activity?