From Napoleon to a lion, how? I've used masks, brushes and the lasso tool to create a seemless transition between the lion's head and background. Since you can't be a true king without a crown I've warped the crown onto his head to create a bit of depth. I've also added skulls, and a snake wrapped around the staff (done by using the dodge and burn tool). Lions are strong animals so I've made the body parts of the king larger by editing the intial layer. By using the bloat tool in the liquidify filter on the intial layer I've made the large muscle areas of the body even larger. The last step was just to bring out the colors more by playing with saturation and levels.
I've used a lot of masks in the second image. Using gradient maps, highlighting shadow and lightsources, and working on color balance made this image seem like a real picture.