If a brain tumor is hugh and makes a knot on your head will it kill you?

Outside skull?: Brain tumors, no matter how huge they get, typically do not cause a knot on your head. Brain tumors can be deadly, yes. Masses (knots) on the outside of your head could be from infection, or bone or soft tissue cancers. Many of these types of cancers are treatable. I strongly encourage you to see a health care provider if you haven't already.

Possible: If a tumor is within the confines of the skull, the downward displacement of the brain stem by the tumor can be fatal, regardless of whether or not it is microscopically benign or malignant. If it is on the outside of the head, and it is benign, prognosis is good.