1. Harry Potter and the Philosopher's Stone by J.K. Rowling
I've read this a few times before so when I re-read it its easy to finish in one sitting.
2. Girl Online by Zoe Sugg
One I recently read and completely adored. I lost track of time and had finished it before I even thought about taking a break. You can find my full review here.
3. The Fault in Our Stars by John Green
I wanted to see the film so I had to race through it.
4. Magyk by Angie Sage
It felt like all the chapters ended on a cliffhanger
5. Delirium by Lauren Oliver.
It was such a gripping read I felt like I wanted to know more.
1. Slammed by Colleen Hoover
This was my first Colleen Hoover book (I am currently reading Hopeless which is not a one sitting book for me) and I loved it. I was so desperate for everything to work out ok and I had to reach the end as soon as possible!
2. Clockwork Prince & Clockwork Princess by Cassandra Clare
I was going away for the weekend and wouldn't have been able to take them with me so I stayed up all night and read them both before going. I was exhausted the next day but it was totally worth it.
3. Harry Potter and the Deathly Hallows by J.K. Rowling
I remember when this came out we had been waiting what felt like forever and I knew my brother wanted to read it as well so I read it the day it came out and passed it on, I am pretty sure he read it in one sitting as well.
4. Madam, Will You Talk by Mary Stewart
She just does mystery so well. I love all her books and I have read them all in one sitting but this was the first of hers I ever read.
5. Sylvester by Georgette Heyer
Another one where any of her books would work. Or in fact any regency romance. Its a genre I always do in one sitting so I have to be very careful not to start a regency just before I go to bed or I won't be going to bed. This was the first Heyer I read and the first regency (unless you count Austen), it was one I didn't especially want to read but I was bored and it was there and then I tore through it.