Oh, you think I missed? Nope! (5e Optimized Character Build)
From D&D Wiki
This power-build requires the core rulebooks and Xanathar's Guide to Everything.
First, you want a halfling. Doesn't matter which subrace, but you need the Lucky trait. Next, grab four levels as a wizard with School of Divination. Portent is essential, and that ability score increase might come in handy. After that grab six levels of fighter for the two ability score increases, and use both to get the Lucky feat from the PHB and the Second Chance feat from XGE. By 10th level, your array of luck-based features makes you quite dangerous. As you continue advancing, grab Bountiful Luck (XGE) at some point and go for at least three levels in rogue, taking the Assassin archetype. If you can, go further in rogue for Uncanny Dodge and Evasion, but the whole rogue plan is a late-game plan of action more than an essential course. All of that stuff helps make you into the ultimate DM headache and annoyance to the monsters, but isn't actually necessary.