Joel Leroy Achenbach (//; born December 31, 1960) is an American staff writer for The Washington Post and the author of seven books, including A Hole at the Bottom of the Sea, The Grand Idea, Captured by Aliens, It Looks Like a President only Smaller, and three compilations of his former syndicated newspaper column "Why Things Are". He is a contributor to many publications, including Slate and National Geographic, where he is a former monthly columnist. Mr. Achenbach has been a commentator on National Public Radio's Morning Edition, and does occasional lectures and other speaking engagements. In addition to his work in the print version of The Washington Post, Achenbach was one of the first Post writers to have a significant presence on the Internet and currently writes the popular Post blog, "The Achenblog".
Achenbach is a native of Gainesville, Florida and graduated from Princeton University in 1982 with an B. A. degree in Politics. Prior to his tenure with The Washington Post in 1990, Achenbach was a staff writer for the Miami Herald from 1982–90, where he worked closely with Pulitzer Prize winners Gene Weingarten and Dave Barry. Achenbach was awarded the Philip J. Klass Award for outstanding contributions in promoting critical thinking and scientific understanding for 2011, by National Capital Area Skeptics (NCAS).
Achenbach is known for his versatility and deft humor. As a reporter and an author he has covered topics as diverse as presidential elections, George Washington, the national deficit, the war in Iraq, the search for extraterrestrial life, the space program, and climate change. In addition to scientific and analytical sophistication, Achenbach's work is characterized by a strong appreciation for and sensitivity to the human aspects of his stories.
In the months after the Deepwater Horizon Disaster, Achenbach wrote and contributed to an extensive series of articles for The Washington Post that led to his most recent book, A Hole at the Bottom of the Sea.
Achenbach lives in Washington DC with his wife and three children.
 Selected works
- Why Things Are (1991), ISBN 978-0-345-36224-7
- It Looks Like a President Only Smaller: Trailing Campaign 2000 (2001), ISBN 978-0-7432-2348-5
- Captured by Aliens: The Search for Life and Truth in a Very Large Universe (2003), ISBN 978-0-8065-2496-2
- The Grand Idea: George Washington's Potomac and the Race to the West (2005), ISBN 978-0-7432-6300-9
- A Hole at the Bottom of the Sea: The Race to Kill the BP Oil Gusher (2011), ISBN 978-1-4516-2534-9
- Achenblog – the official Joel Achenbach blog
- Video discussions and debate featuring Achenbach on BloggingHeads.tv
- Official website for "A Hole at the Bottom of the Sea"