As fast as an eagle, as slow as a slug. As tall as a tree, as small as a bug. Sometimes in front, sometimes behind. Never on top, and always aligned. What is it?

What's black and white and red (read) all over?

I am a vicous man-killer when i am angry but I am gentle and calm when I am happy. I can be a home pet but my fangs dont suit the job. I have a legend about me but I know it might not be true.

I may look scary but I am not really that scary. I may walk into your garden but then I would tell a lie.

What am I ?