Leonard S. Peikoff (born October 15, 1933) is a Canadian-American philosopher. He is an author, a leading advocate of Objectivism and the founder of the Ayn Rand Institute. A former professor of philosophy, he was designated by the novelist Ayn Rand as heir to her estate. For several years, he hosted a radio talk show.
References in some parts of Lecture 1 may not make sense if you haven't studied Modern Philosophy before (Pragmatists, Logical Positivists, Analysts, and Existentialists), but the rest of the course is self contained.
If you're short on time, consider going through at least the lectures on Informal Fallacies and on Definitions.