Zombie

Zombies only appear in surface-level biomes during the night time and are one of the first monsters a player will encounter. Their preferred attack pattern is to move towards the player; jumping rather high to accomplish this. They can navigate Wood Platforms. They also try to open Wooden Doors, but can only succeed during a Blood Moon. They will always leave at dawn, even if half-way through attacking a player, or if they can't find any clear path to the player (However, this only works with blocks, they will always try to break Wooden Doors even if they will not suceed outside of a Blood Moon)

Strategy
Zombies should not be underestimated, especially by new players. While they may move slowly, they are surprisingly good jumpers. They also have a fair amount of hit points, good defense and a pack quite a punch.

That being said, a simple Wooden Sword swung repeatedly is enough to keep one or two zombies at bay. Three or more zombies bunched up, however, will likely be able to get past and cause damage. In this situation, weapons that pierce through or hit multiple enemies work best. If you were lucky enough to find a Spear, it can keep any number of Zombies at bay. Throwing weapons such as Shurikens and Throwing Knives also work well against groups of zombies.

Blood Moon
If one wishes to avoid zombies entirely during a Blood Moon, covering doorways with any material such as Dirt or Stone will stop the zombies from entering your home. Placing a Wood Platform or other piece of furniture next to the door will also prevent a zombie from opening it.

Also placing a door above the ground level, or digging a trench that is the height of 2 blocks forces them to jump at the door, during which they can't open your door.