You may be one of the million of National Novel Writing Month participants living with Post NaNoWriMo Letdown Syndrome.
Don’t suffer alone!
— B. C. FORBES
(aka, it’s OK if you didn’t win NaNoWriMo this year)
Ricky Gervais on writing what you know
In your BOOK, people. Killing a character can be great for the word count: finding the body, planning/attending the funeral, mourning, and the aftermath of what the death means for the other characters are all very wordy prospects. It doesn’t have to be depressing, all of these can be played for comedy dark or otherwise, but it’s a great way to get your pen moving even if it feels like your book is already flat-lining.
But from a big picture standpoint, killing a character forces you to shake things up and throw your characters a curve ball. When you get them out of their rut, how do they behave? It can help you discover the path back to where you needed to be.
In general, any time you can throw your MC’s world in turmoil, the story will be better for it.