The worldly philosophers
The book starts by looking at the work of Adam Smith, but then moves on to more pessimistic views such as those of Thomas Malthus and David Ricardo. There's a chapter on the Utopian visions of Robert Owen and J.S. Mill, and, of course, a description of the ideas of Karl Marx. The book moves on through the Victorian era to the 20th Century with a look at the work of Thorstein Veblen and then gets to the more modern ideas of John Maynard Keynes and Joseph Schumpeter. The final chapter, added in the 7th edition, looks at the future of economics.
I wasn't convinced that the last chapter added much of value to the work, but overall the book is well worth reading. The choice of the important economic thinkers is well made, and the inclusion of plenty of biographical material makes the book an accessible introduction to the development of economics. I wish that similar books were available for other subjects.