It's the duty of the Lord Commander
to fill those pages.
Game of Thrones Season 4, Episode 4
I expect she's headed to Castle Black
where her brother serves as Lord Commander.
Game of Thrones Season 6, Episode 4
As Lord Commander
of the Night's Watch,
Game of Thrones Season 7, Episode 2
I'm not Lord Commander anymore.
Game of Thrones Season 6, Episode 4
Half the men hate you already,
Lord Commander.
Game of Thrones Season 5, Episode 5