Everyone else who’s answered this question has been very decisive, but I really can’t choose an particular science TV series. I’ve always loved Nova, Nature, National Geographic, and I remember watching and loving Marty Stouffer’s Wild America on Sunday mornings when I was a kid. But I think my favorite science show episode of all time was the 1991 National Geographic special, “Eternal Enemies: Lions and Hyenas“. It was amazing to watch those two powerful species go at it. Here’s a part of the special: