[Numberphile podcast](https://www.numberphile.com/podcast) by Brady Haran

[My Favorite Theorem](https://kpknudson.com/my-favorite-theorem) by Kevin Knudson and Evelyn Lamb (in each interview, a mathematician shares their favorite theorem)

[The Joy of $x$](https://www.quantamagazine.org/tag/the-joy-of-x/) by Quanta Magazine. Steven Strogatz interviews scientists (not exclusively mathematicians, but so far, including a disproportionately high number of mathematicians)