Ryuk is my favourite character from the anime DEATH NOTE. Oh, you don't know Ryuk? let me introduce him to you:
Ryuk (リューク, Ryūku ) is the main Shinigami of the Death Note series. Bored with the activities (or lack thereof) of the Shinigami realm, Ryuk obtains a second Death Note and drops it in the human realm for someone to find, hoping to amuse himself. He deliberately writes the instructions on the front page (in English, which he assumed to be the most popular language in the human realm) so people would understand its purpose. The Death Note is discovered by Light Yagami, and Ryuk follows him around for much of the series to see how Light uses it. Ryuk has a fairly humanoid appearance. His skin is gray, or a purplish color, his limbs are abnormally long, and he has bulging yellow eyes with black irises (red in the anime); in the films, he is represented by CGI. He is voiced by Shidō Nakamura in the Japanese anime and live-action adaptations, while Brian Drummond voices him in the English dub. - wikipedia
Ryuk is characterized by his constant amusement by, and apathy in regards to, Light's problems. He enjoys seeing Light overcome the various challenges put to him, and often waits until the worst possible moment to inform him of a certain aspect of the Death Note just to get a laugh. He is occasionally helpful if it serves his own interests, such as obtaining apples or furthering his own amusement, but for the most part will jokingly ask Light what his next move will be or have Light explain to him the point of a certain action. The sfist describes Ryuk as a "crazy-looking, supernatural creature with these wicked eyes" who becomes "(surprisingly)" a "moral compass" for Light in the film version of Death Note. - wikipedia
Ryuk has a great fondness for apples, comparing them to cigarettes and alcohol for Shinigami (Shinigami apples are withered and taste like sand, as he shows Misa at one point), and will go through a type of withdrawal if he goes for too long without eating them. His withdrawal symptoms involve twisting himself up like a pretzel and doing handstands. He also states that he is shy around girls. In addition to apples, Ryuk is fond of video games, first shown in the omake eight-panel comic series, where he asks for a Silver Game Boy Advance SP, originally published in Weekly Shonen Jump Volume 4-5 (double issue) in 2005. On another occasion, Ryuk asks Light if he wants to play Mario Golf (changed to "video games" in the anime), but receives no answer since Light's bedroom is bugged with cameras. - wikipedia
As Ryuk explains when he first meets Light, he is bound to take Light's life when his time comes. In the manga, Ryuk does this after Light is shot several times by Matsuda. He desperately begs Ryuk to write the names of the investigation team and the SPK members in the Death Note, but Ryuk, reminding Light that he is not on anyone's side, just writes Light's name instead. He was expecting Light might have thought of some way out of his situation, but seeing as he was desperate enough to go to Ryuk for help, he decided it was all over for him. Ryuk returns to the Shinigami realm. - wikipedia
In the anime, Light does not ask for Ryuk's help and manages to escape the warehouse thanks to Mikami's suicide distracting everyone else. However, his wounds are too severe for him to escape very far, and Ryuk, who is watching him from atop a pole, decides that following Light around during a prison sentence is not worth his time and thus writes Light's name in his Death Note. Light dies peacefully, with an apparition of L standing over him - mirroring Light standing over L on his death.
The second film ends in much the same manner as the manga, except Ryuk's silence leads Light to believe that he is willing to help. When Light learns differently, Light yells at Ryuk and jumps through him, trying in vain to stop his death before dying in his father's arms; before this, Ryuk takes this opportunity to reveal to Light that humans who have used the Death Note are unable to enter either Heaven or Hell regardless of their actions in life. In the spin-off L: Change the WorLd Ryuk offers L the Death Note, but when L refuses and proceeds to burn it, Ryuk moans about L being boring and disappears, returning to the Shinigami realm.Tsugumi Ohba, story writer of Death Note, said that Ryuk is his favorite Shinigami and that "If I didn't say Ryuk here, his whole character would be in vain. - wikipedia