What are you playing? c'mon, tell me punk!

[E-Man]

You must have met a Treeguard. They're very powerful, but not so bad if you know how to deal with them. Just make sure you don't chop down too many trees after the third day and plant plenty of pinecones. Also, even if a Treeguard does show up, its slow speed shouldn't give you much trouble as long as you keep moving. Also, if you could lure him into a pig village or an open fire (i.e. a campfire), you should have a chance at defeating it.

By the way, if you actually manage to defeat one for yourself, you'll score a lot of living logs, which are actually used to craft some really amazing items.