Finn from Five Flavors of Dumb by Antony John
I feel like my keyboard will break from the number of less-than-threes I want to type, he's supportive and just a superb younger brother. I loved that he would always help out Piper and that sometimes he was a brat and troublemaker but has a heart of gold.
Finn from In Honor by Jessi Kirby
I mean, he's dead (not a spoiler). But I still ended up loving him because of the love he extended to Rusty and how much he cared about Honor. He was thrown with so much responsibility at a young age but never backed down, and he spent his life making sure Honor could have the best one. It's just... asdkjf;alksdjf;ajl
Finn from Finnikin of the Rock by Melina Marchetta
Come on, what a hero (albeit not exactly a brother). He's older and wiser beyond his years from all the stuff he's had to endure through the years, traveling and learning the history of his land. He is the one who's trying to piece his kingdom back together and he's just a freaking teenager. He's basically awesome.
Finn from The Scorpio Races by Maggie Stiefvater
Perhaps my favourite Finn. I can't even name the number of reasons he just steals my heart, from the fact that he'll fight with Puck and he'll fight for her. He'll try and do what's best for his family and his sneaky side where he'll scam a few more November Cakes for himself. I love how Stiefvater gave him such personality and depth even when he wasn't the main character, and well, he stole some scenes for me. Love this Finn.
"One of the lines in Finn's code is that you're not to say anything about Finn being attractive to the opposite sex. I'm not sure which exact statue governs this, but it's closely related to the one that won't let you thank him.
Something about compliments and Finn don't work."
Which basically concludes I really should name my kid Finn, eh? And of course, please mention any other Finns I have forgotten and deserve to be on the list :)
 HOW COULD I FORGET FINNICK ODAIR HOWWWW <3 (thanks elena for the reminder!)