Henley

Rag & Bone Raglan Henley
But It Now at Rag & Bone, $150 

Winter is simply way too cold to rock a simple v-neck underneath a blazer. For a similar casual vibe, opt for a henley. Whether it's the thermal waffle-knit version or just a simple ribbed knit, it'll keep you looking put together without making you seem like a slob.