In anime, many characters change their proportions freely according to their feelings and when the scenes call for an extra level of cuteness or what not. You may have seen many merchandise and spin-off series of popular anime characters being designed and drawn in the super deformed style.
There is one distinguished style of deformation of a character and it is called "Chimi Chara". One of the most recent collaboration is with Noitamina's PSYCHO-PASS for its spin-off game, appropriately titled, "Chimi Chara PSYCHO-PASS".
Original character design of PSYCHO-PASS:
After Chimi Chara-nization:
The designer behind this phenomenon is Yu-pon, a resident graphic artist at Nitroplus, a Japanese visual novel software company responsible for titles such as Guilty Crown Lost Christmas and the Fate/Zero novel. His Chimi Chara design is so popular, you may have already seen your favorite character as a Chimi Chara.
Here are some examples of his work.
Uta No Prince Sama Maji LOVE 1000%
Photos of other characters, here.
Chimi Chara Fate/Zero by Mega House
Even a brute like Kiritsugu can be this cute.
Awww, Kiritsugu doesn't even look like he can kill a bug.
Yu-pon sometimes works with real people, too.
GRANRODEO, a rock band of the voice actor, Taniyama Kishow
Joy Max, the beloved and the best Nitroplus PR person
Other titles he worked on taken from the Chimi Chara site.
Yu-pon also did illustration for Puella Magi Madoka Magica novel with his non-Chimi Chara style.
Look out for more of his awesome work in the future!