Merge/diff tool that can show authors (supports blame or annotate) in files under version control

Question

When merging files it will be helpful (as for me) to show an author of each line. Is there any diff or merge tool supporting that?

Answer 1

The bundled gitk tool is not really a merge tool, but it shows conflicted lines with red and blue and "+"'s in front, and you can Rightclick->"Show origin of this line" on any of them, to go to the commit which introduced the line:

You can run your mergetool, or just a text editor with diffmarks in parallel