BBC America, 6:00 a.m. ET
Well, when a TV show’s season is only three episodes long, a “marathon” showing of an entire season is less a marathon than a sprint. But BBC America is showing more than one season of Sherlock, the brilliant modern reinterpretation by Mark Gatiss and Steven Moffat. Benedict Cumberbatch and Martin Freeman star as Holmes and Watson, and the marathon begins with “A Study in Pink,” which reintroduced the Baker Street sleuth in his newest, and best, TV incarnation. Watch, in particular, for the Season 2 opener “A Scandal in Belgravia,” which first presented Lara Pulver as Irene Adler – and did so without breaking the budget on wardrobe. It's repeated at noon ET.
HBO, 9:00 p.m. ET
SEASON FINALE: This series ends its first season with an episode that, as much as any other this year, pulls the rug out from under the viewer by refining a major character’s background and motivation. James McAvoy’s Lord Asriel is one of the characters to keep an eye on… but surprises, in this Season 1 finale, come from many directions, so grin and bear it. (Bear. See what I did there?)