I recently discovered the quotes of H.L. Mencken. He’s absolutely brilliant. I can’t believe that in my 34 years, I hadn’t seen a list of his quotes. It makes me wonder who else’s quotes have eluded me thus far. So, do you have a favorite quote-originator? Who?, and give an example or two.
Tx.
Bill Watterson of Calvin and Hobbes fame:
“From now on, I’ll connect the dots my own way.” (My high school grad quote)
“Know what I pray for? The strength to change what I can, the inability to accept what I can’t and the incapacity to tell the difference.”
I love a good quote. Dorothy Parker could write some real gems… many of which are in a Barbed Quotes book I recently purchased.
My favorite quote that immediately leaps to mind is from Red Skelton. Large crowds at the funeral of a despised studio head prompted him to say “It just goes to show you if you give the people want they want, they’ll come out.”
Kurt Vonnegut:
"With every passing hour our solar system comes forty-three thousand miles closer to globular cluster M13 in the constellation Hercules, and still there are some misfits who continue to insist that there is no such thing as progress.”
Charles Dickens:
“Still, looking forward through this intermediate stage, to the time when there should be a perfect sympathy between Dora and me, and when I should have ‘formed her mind’ to my entire satisfaction, I persevered, even for months. Finding at last, however, that, although I had been all this time a very porcupine or hedgehog, bristling all over with determination, I had effected nothing, it began to occur to me that perhaps Dora’s mind was already formed.”
Terry Pratchett!!!
Try here for the best, or see my sig line. 
What our ancestors would really be thinking, if they were alive today, is: “Why is it so dark in here?”
– (Terry Pratchett, Pyramids)
All dwarfs have beards and wear up to twelve layers of clothing. Gender is more or less optional.
– (Terry Pratchett, Guards! Guards!)
Oscar Wilde has some really good ones…
A cynic is a man who knows the price of everything but the value of nothing.
A little sincerity is a dangerous thing, and a great deal of it is absolutely fatal.
A true friend stabs you in the front.
Always forgive your enemies - nothing annoys them so much.
Every saint has a past and every sinner has a future.
Just a few of my favorites…
Winston Churchill
Mark Twain
W.C. Fields
Groucho Marx
This site Has all of those people(minus Churchill) and a few others.
Gotta be.
“Diplomacy is just lying for a better class of people.”
See, these two pompous, faux-modest quotes of hers always annoyed the hell out of me:
“Acting is the most minor of gifts. After all, Shirley Temple could do it when she was four.”
“Acting is the perfect idiot’s profession.”
It was an easy profession for her: she breezed into New York with perfect bone structure and her family’s money, and didn’t have to wait tables or work at Woolworth’s like other young actresses. And frankly, Katharine Hepburn wasn’t even a good actress till the 1940s.
There was much that was admirable about her, but bad-mouthing her profession wasn’t one of them.
You may not recognize the name, but you’ll recognize many of the quotes. (Best known: “If you steal from one author, it’s plagiarism; if you steal from many, it’s research.”)
Mark Twain.
Robertson Davies
Charles Dickens
Winston Churchill
Reiner Maria Rilke
William Shakespeare
Robert Frost
I would second Rhiannon8404’s nomination of Oscar Wilde.
I would also nominate Nietzsche, though some of his aphorisms are better than other ones (and some, especially his comments about women, make me cringe).
Learn to say no. It will be of more use to you than to speak Latin.
Unknown… at least to me. If anyone knows who said this, I would be interested.
And don’t say no. 
My two current favorite quotes are:
“So I prayed; I did not pray to get my own way, because I am smart enough to know that that is not always in my best interests.” -Anne Lamott
and
“Cats aren’t clean; they’re just covered with cat spit” -John S. Nichols
(I have no idea who he is, I just love the quote.)
Terry Pratchett, Lois McMaster Bujold, Janet Evanovich, and a few more here and there