Death & Co.
433 E. 6th St. (btw Avenue A & 1st Ave.)
One of the more famous speakeasies in NYC and one of the hardest to get into - plan on waiting and don't come with a big group (but they will text you when a table is ready). If your'e only in the mood for cocktails, I suggest trying out Amor & Amargo while you wait. They take their cocktails seriously and the high price tag reflects that.