The buzziest history podcast around recently -- judging by the media I see or follow -- must be "Empire," a British project of the historian of South Asia William Dalrymple (pronounced more like "Drymple" judging by how he introduces himself) and Anita Anand (the British TV presenter, not the Canadian politician). Recently their empire of choice was the Russian one, and their guest was starry historian Simon Sebag Montifiore (who uses "Sebag," not "Simon," as his given name, who knew?). Now they are onto the Raj, but still with a focus on Russia and "the great game" (as only the British would name a long cycle of imperial conquests). In the reigning podcast fashion it's chatty, funny, a bit show-offy, full of laughter and fairly superficial as history, but undoubtedly listenable.
For a more intense, sit up and listen history podcast, I go to Patrick Wyman's "Tides of History." Wyman starts each episode with an intense little imagined scene, and then plunges directly into deep and very academic-research-driven discussions of ... well, whatever takes his interest. He's followed the Polynesian expansion across the Pacific, Medieval Europe, the Bronze Age collapse of circa c1200 B,C., and the Paleolithic, among many other periods, with excursions into interviews of archaeologists, linguists, and whomever ever catches his interest.
CanHist podcasting? Though I'm a longtime member, occasional beneficiary, and constant admirer of the Osgoode Society for Canadian Legal History, I've just learned they too are doing a podcast, "Time Immemorial," presented by two young lawyer-scholars, Preston Lim and Gregory Ringkamp. I have not listened yet, but they look to be deep-divey examinations of various Canadian and Canadian moments, generally with some legal-history aspect.
The Champlain Society's "Witness to Yesterday," led by Patrice Dutil and Greg Marchildon, is the granddaddy of in-depth history podcasting in Canada, as far as I know. These days, they seem to interview everybody who publishes a worthwhile history in Canada (me included. Thanks, guys.)
It's a growing field and still largely uncategorized, podcasting. What history podcasts are in your earbuds?
Update, September 19: Meant to include: For a real deep dive into niche podcastery by an obsessive Englishman named Andrew Hickey, try "A History of Rock and Roll in 500 Songs." (New Yorker: "his project is so vast that it can only be compared to, say, the construction of the Oxford English Dictionary.")