What is that thing called?

I’m having a brain fart at the moment and cannot recall what this thing is called. It’s not the title of the book, but it is the “tagline” normally written in smaller print on the cover. An example something like, “He fought the law - and won!”

Any help would be appreciated.

Um, subtitle?

Derp! There you go. I think that’s it.

Actually, from the example in the OP I’d say no. A subtitle is an alternate title, usually longer, and will normally start with or as in “Dr. Strangelove or: How I Learned to Stop Worrying and Love the Bomb” or “Oliver Twist; or, The Parish Boy’s Progress”.

I think what you have there is a blurb, which is a kind of advertising byline:

In newspapers and magazines, a secondary title line is sometimes called a kicker. In traditional newspaper usage that goes above the main headline.

Non-fiction works often have a brief main title that is often intended to be eye catching and ‘clever’ in some way, followed by a colon and then a subtitle that actually directly states what the book is about in a duller, more literal way.

I think you are right that what the OP describes is not a subtitle, but I think a blurb is usually something a good deal longer: a brief paragraph at the least, giving either a synopsis of the contents or extolling them (or both). Blurbs are usually on the back cover or the inside flap of a dust jacket.

I think Mr Downtown’s suggestion is more like it, although strap line or catch line are also possibilities.

Those are not subtitles, They are parts of the titles.

Then what are subtitles? Nothing I have seen lists those as part of the actual title.

Heck, even Wiki lists those two as examples in its subtitle article, albeit without sources.

It’s a matter of interpretation. Some librarians would call them subtitles like whoever has catalogued “Dr Strangelove” for the British National Bibliography. I would hesitate to do it as they look more like some kind of alternate titles.

A better and less ambiguous example from my desktop: http://i127.photobucket.com/albums/p157/Floater_photo/02082011225.jpg. Here there’s no question of what is the main title and what is a subtitle.

Or a deck:

BUS PLUNGES INTO RIVER
All passengers believed dead

Floater is correct. Both of those examples are what librarians call alternative titles. AACR2 defines it this way:

Alternative titles are marked by a very specific syntax in library catalogs: comma space “or” comma. As in

Maria, or, The Wrongs of Woman / by Mary Wollstonecraft.

In cataloging it’s handled differently from a subtitle. For one thing, alternative titles get added title entries, while subtitles don’t.