Cosmos by Carl Sagan

The Lord of the Rings, for sure. But then I did not read for a few decades, and recently got back into reading thanks to audiobooks. Since then, the first book that I loved every moment of was The Lies of Locke Lamora.

The Velveteen Rabbit

I remember being 12 or so and when I finished The Lord of the Rings, I felt a sense of loss. I just wanted the book to go on forever. I suppose that is the first book I truly loved.

Illuminatus!... At the age of 11.

Adolescence felt pretty straightforward after a book like that.

The Mouse and the Motorcycle

The Six Bullerby Children by Astrid Lindgren. I was maybe 9 at the time. I should reread it someday.

The Little Prince.

Read it as a child. Cover to cover. Painstakingly sounding out each word. Repeatedly. Then for years I forgot about it.

As an adult I came across it in my bookshelf, buried deeply (it having fallen down the back a bit) and read it again. It is a completely different book when you read it as an adult…

2nd time I see this question, so my answer is my second book:

The color of magic by Terry Pratchett

Bridge to Terabithia. Yeah, I was a kid, but I cried when a main character died.

War of the Worlds

Probably Northern Lights (the first of His Dark Materials - Philip Pullman or maybe Bloodtide - Melvin Burgess. I'm a sucker for alternate/near future reality and world building and these both did it really well.

“So you want to be a wizard” by Diane Duane. Opened my eyes to magic systems that just aren’t just hocus pocus and wand waving. Remarkably well designed for YA.

Urban fantasy with well thought out magic systems are still my favorite type of books to read today.

As a child my favorite books(and thus the first ones I remember loving) were:
Harold and his Purple Crayon
The Monster at the End of the Book
and The Giving Tree (which admittedly has a much different meaning to me now)

The first “grown up” book I remember reading and loving (at ~11) was Watchers by Dean R. Koontz

My favorite books as an adult are:
Sirens of Titan by Kurt Vonnegut
and The Watermelon King by Daniel Wallace

First? The Spaceship Under the Apple Tree. I read the Oz books pretty early. I read all the Sherlock Holmes books in junior high, I think.

Can’t remember the name of it, but it was about a mouse who went surfing on a tongue depressor/popsicle stick. Checked it out repeatedly from the school library in first grade.

Unfortunately, Harry Potter. Was so confused when You-Know-Who came out as an absolute piece of shit. I couldn't agree with her bullshit and didn't want to stop loving what I used to say was my favourite book.

The Bodyguard by William C. Dietz - literally the only book I have read more than once, and I may have read it at least 4 times.

The Swiss Family Robinson. My father read me a chapter each night & it was one of my fondest memories.

Where.The Red Fern Grows
By Wilson Rawls

Loved it at about 12. Read it twice. 👍

I didn't really love reading until I hit my 20s. A Brief History of Time really did it for me.

Peter Carey - The unusual life of Tristran Smith