Looking for the best first novels.

I'm gearing up for an essay about first novels and looking for recommendations for the best first novels. Give me your top two. One by a writer considered a pillar of genre fiction and one by a more contemporary writer. Use your own criteria for those. Oh, I'm looking for the writer's first published book, not the first book in a given series.

Here's my list so far:

* *The Color of Magic* by Sir Terry Pratchett * *Gideon the Ninth* by Tamsin Muir * *Old Man's War* by John Scalzi * *Legends and Lattes* by Travis Baldree * *A Long Road to a Small Angry Planet* by Becky Chambers * *40* by Alan Heathcock * *Caesar* by Patrick O'Brien * *Lies of Locke Lamora* by Scott Lynch