12 TV shows that have just been canceled

It's that time of year when the broadcast networks are bringing down the ax on several of their series.

In order to make room for new series and prepare for this month's presentation to advertisers, executives have been crunching the ratings numbers, checking their pilot inventory, and making both easy and difficult decisions on which shows have to go.

Some of the surprises of this season are ABC's dumping of "Castle," "Marvel's Agent Carter," and "Nashville" for low ratings and high budgets.

And Fox killed its Rob Lowe and John Stamos comedy vehicles, "The Grinder" and "Grandfathered," respectively. Despite critical and fan acclaim, and a lot of promotion, people weren't tuning in.

Here are the 12 biggest cancellations of the season so far:

We'll update this story as networks announce decisions.