The Muppets are mix of different species. Some are ostensibly human (or at least Muppet versions of humans), like [Statler and Waldorf][1].

[![enter image description here][2]][2]

Some belong to other subsets of the animal kingdom, like [Kermit the Frog][3], who's been clearly identified as a frog at various times, like in _[The Muppet Movie][4]_ (credit to PlutoThePlanet for this one), and a more recent interview with Ellen DeGeneres.

[https://www.youtube.com/watch?v=2fwq7YY2Suc][5]

[https://www.youtube.com/watch?v=1_AUn5poOmA][6]

And some are alien, like [Gonzo][7], whose extraterrestrial origins were revealed in _[Muppets from Space][8]_.

[https://www.youtube.com/watch?v=Lx2jYCltuQo][9]


  [1]: https://en.wikipedia.org/wiki/Statler_and_Waldorf
  [2]: https://i.sstatic.net/0ZVoU.jpg
  [3]: https://en.wikipedia.org/wiki/Kermit_the_Frog
  [4]: https://en.wikipedia.org/wiki/The_Muppet_Movie
  [5]: https://www.youtube.com/watch?v=2fwq7YY2Suc
  [6]: https://www.youtube.com/watch?v=1_AUn5poOmA
  [7]: https://en.wikipedia.org/wiki/Gonzo_(Muppet)
  [8]: https://en.wikipedia.org/wiki/Muppets_from_Space
  [9]: https://www.youtube.com/watch?v=Lx2jYCltuQo