Terry Pratchett’s magnum opus: one of the best, and definitely the funniest, fantasy series of all time.

If you’re just wanting to follow the exploits of a single character, try the Discworld Character Guide.

Small Gods
Novel published in 1992.
The events of Small Gods take place decades (or more) earlier than most other Discworld stories, leading to its placement here. However, stylistically-speaking – and in the case of a single time-travelling character – it may make more sense to read it in publication order. Hence, it is listed at both points in this Reading Order.
The Colour of Magic
Novel published in 1983.
The Light Fantastic
Novel published in 1986.
Equal Rites
Novel published in 1987.
Mort
Novel published in 1987.
Sourcery
Novel published in 1988.
Wyrd Sisters
Novel published in 1988.
Pyramids
Novel published in 1989.
Guards! Guards!
Novel published in 1989.
Eric
Novel published in 1990.
Moving Pictures
Novel published in 1990.
Reaper Man
Novel published in 1991.
Witches Abroad
Novel published in 1991.
Small Gods
Novel published in 1992.
This is where Small Gods falls in publication order. However, the events of the book take place decades (or more) earlier than most other Discworld stories, hence it is listed at both points in this Reading Order.
Lords and Ladies
Novel published in 1992.
Men At Arms
Novel published in 1993.
Soul Music
Novel published in 1994.
Interesting Times
Novel published in 1994.
Maskerade
Novel published in 1995.
Feet of Clay
Novel published in 1996.
Hogfather
Novel published in 1996.
Jingo
Novel published in 1997.
The Last Continent
Novel published in 1998.
Carpe Jugulum
Novel published in 1998.
The Fifth Elephant
Novel published in 1999.
The Science of Discworld
Novel published in 1999.
The Truth
Novel published in 2000.
Thief of Time
Novel published in 2001.
The Sea and Little Fishes
Short story originally published in 2002.
The Last Hero
Novel published in 2001.
The Amazing Maurice and his Educated Rodents
Novel published in 2001.
Night Watch
Novel published in 2002.
The Globe: The Science of Discworld II
Novel published in 2002.
The Wee Free Men
Novel published in 2003.
Monstrous Regiment
Novel published in 2003.
A Hat Full of Sky
Novel published in 2004.
Going Postal
Novel published in 2004.
A Collegiate Casting-Out of Devilish Devices
Short story originally published in 1998.
Thud!
Novel published in 2005.
Where’s My Cow?
Storybook published in 2005.
Darwin’s Watch: The Science of Discworld III
Novel published in 2005.
Wintersmith
Novel published in 2006.
Making Money
Novel published in 2007.
Unseen Academicals
Novel published in 2009.
I Shall Wear Midnight
Novel published in 2010.
Snuff
Novel published in 2011.
Raising Steam
Novel published in 2013.
Judgment Day: The Science of Discworld IV
Novel published in 2005.
The Shepherd’s Crown
Novel published in 2015.