Ryuk

Origin

After Light Yagami discovered Ryuk's dropped the Death Note, he spent 6 years as the self declared god of death Kira. But after nearly being discovered by L time and time again over the years and ultimately discovered by Near, and shot multiple times by the police, Light discovered Ryuk's statement to be very true "someday I will write you in my Death Note" Light found himself victim of the Shinigami he thought to be his ally, Ryuk.

Ryuk also has an obsession with Apples..... and if he does not eat Apples for prolonged periods of time, he has withdrawls. No one is quite sure as to why he loves Apples in such a way but he does regardless 
 

Creation 

Ryuk was created by writer Tsugumi Ohba, and artist Takeshi Obata for the Death Note books. A Shinigami, Ryuk is a Death God. Originally Ryuk was conceived to be younger look, more attractive, and essentially a dark haired, mirror of Light, however his development in the creative process, saw him grow larger, and more monstrous. He is meant to have somewhat of a Rock Star look. Another idea that was floating around when creating the character, was that he may be wearing a mask, to hide a much more attractive face underneath.  
 

Powers and Abilities 

Incredibly long lived, with the ability to fly. Ryuk is a Shinigami. Although his powers are somewhat ambiguous, by virtue of being a death god, its reasonable to assume he has great supernatural power. He can not be harmed by conventional human weapons. 
 

Media 

Death Note Movies

Death Note: Ryuk intentionally dropped his book in the human world because he was bored, Light Yagami picked up the book and became Kira, executing criminals with the Death Note. Ryuk eventually made his presence known to Light, and took joy in Light's life, especially when Light was nearly caught.

Death Note II The Last Name: Ryuk and Light remained companions at the beginning of this movie, but as the events of a 2nd Kira (Misa Amane) unfolded, Light and Misa were found out by L, and were forced to give up their Death Notes, later after Light killed the third Kira who had taken ownership of Misa's Death Note, taking it as his own, and Misa claimed Ryuk's Death Note as her own, also making the "eye deal" with Ryuk. In the end, when it was discovered that L had written his own name in the Death Note and faked his own death with the help of the Shinigami Rem, Light was revealed to be Kira, and called out to Ryuk after being shot, Light told Ryuk for the fun to continue all Ryuk would need to do is write one more name in the Death Note, Ryuk wrote a name, the name was Light Yagami. Ryuk then revealed an unwritten rule of the Death Note, A human who uses it can neither go to Heaven or Hell, and when they die simply cease to exist.