There are 14 15-letter words that start with 'the'.
Note: These 14 15-letter words that start with 'the' are found from the USA & Canada version of the tournament Scrabble word list.
Also see words start with ther, theo, thea, thei, then, thes, them, thec, theu, thew, thee, thet, theb, theg, thef, thel, they.
4-letter words start with 'the' (5)