Would anyone be able to recommend the best and most comprehesive books on both Arthurian legends and Greek mythology? Rather than some type of encyclopaedia I'm hoping for books that tell the legends themselves like Hercules, Achilles, Arthur, Lancelot, Merlin etc.

And I totally blame F/SN for this desire.

 

Monty Python and the Holy Grail, your one stop source for anything you need to know about everything.

 

Edith Hamilton's Mythology tells a lot of the Greek myths and I recommend it as it gives quite a large survey. Ovid's Metamorphoses is also pretty good from what I hear. To learn about Achilles, you should obviously read the Iliad as that book is pretty much about him.

The major Arthurian myth book is undoubtably Thomas Malory's Le Morte d'Arthur.

 

"I fart in your general direction." <-- one of the best lines in the history of cinema.

Seconded. Bullfinch's Mythology is also pretty good but oh-so-dated.

Or if you're pressed for time, just rent The Sword In The Stone - a no-nonsense approach to the legend, foregoing speculation and sensationalized hyperbole in favor of the concrete facts about Merlin and Wart, who of course later became King Arthur.