1. (n.) One who commits a trespass

2. (n.) One who enters upon another's land, or violates his rights.

3. (n.) A transgressor of the moral law; an offender; a sinner.

Dutch uncle Paul Polonius admonisher adviser backseat driver butt-in confidant consultant counsel counselor crasher encroacher expert gate-crasher guide infiltrator instructor interloper intermeddler intruder invader kibitzer meddler mentor monitor nestor nose orienter pragmatist preceptist prier quidnunc rubberneck snoop teacher trespasser unwelcome guest