Harry Potter.
I resisted reading them for years because I hate hype and was rebelling against all the people telling me "You'd love it - it's right up your street - you really MUST read it..." They annoyed me so much I just dug my heels in and refused.
DH didn't realise I was actively refusing to read them and assumed I just hadn't got around to it, too busy, too many books on the shelf waiting to be read etc, and he bought me the first 3 for Christmas. Didn't want to snub his thoughtful gift so I grudgingly read the first one...
And the rest is history. A total Potterhead was born.