Canon now makes two pancake lenses for the EOS mount. Both are just slightly wider than "normal", f/2.8, metal builds, and come with the STM focus motor. Both have reviewed quite well for sharpness and overall image quality; see the-digital-picture.com reviews for the 40/2.8 and the 24/2.8.
The EF 40mm f/2.8 STM is for full-frame cameras.
The EF-S 24mm f/2.8 STM is for crop cameras.
Voigtländer makes three pancake SL II lenses, the Color Skopar 20/3.5 and 28/2.8 and the Ultron 40/2, but these lenses, while they do communicate with the camera body to allow aperture control and metering, do not autofocus. And, of course, adapting pancake lenses, such as the Nikon or Contax/Yashica Zeiss 45/2.8 lenses, or any of Pentax's pancake offerings would be manual focus/aperture with non-reporting lenses, so not nearly as convenient to use as Canon's offerings. In addition, the CZ Tessar 45/2.8 does not have mirror clearance on a Canon 5D body.