"How I Met Your Mother" (8 p.m., CBS):
Here's the episode where we really get to know the Mother (Cristin Milioti) as we learn what has been going on with Ted's (Josh Radnor) future wife the past eight years.
"Herblock: The Black & the White" (9 p.m., HBO: The compelling new documentary traces the life, times and influence of celebrated editorial cartoonist Herbert Block. His career spanned over 50 years and earned him a Pulitzer Prize.
"Castle" (10 p.m., ABC): In an episode titled, "Dressed to Kill," Castle and Beckett (Nathan Fillion, Stana Katic) investigate the murder of a fashion magazine editor's assistant. Frances Fisher guest stars as the intimidating editor.
Also on Monday: