Age: 45-60. Probably. It's hard to tell with rats...
Gender: Male
Dessert: Fortune Cookie. What else?
Magazine: Natural Health, Smithsonian
Weapon: His walking stick probably stands out, but he doesn't really need a weapon.
Character: Think Yoda with fur. He's the quintessential guru-type. A father figure to the turtles, as well as a teacher, therapist and spiritual guide. I'm inclined to say that he's a Zen Buddhist. It seems more likely than Shinto (the indigenous Japanese religion) because he is very into simplicity of lifestyle, discipline and meditation. Zen is also, I think, the most common form of Buddhism in Japan. I could be wrong. Depending on the series he's either a mutated Ninja master and former comrad of the Shredder, or the former pet rat of a Ninja master who was in competition with the Shredder.  He's got a Japanese accent which tends to vary in extremity depending on the series.

Images: (artist's name in parenthesis. Unless it's from one of the 'toons. In that case, I have no idea.)

Threatening: Splinter meets Casey for the first time. He makes quite a first impression.
Talking: From the first 'toon. Forgive the subtitles, they were there when I downloaded the episode. I have no idea what language it is, either.
Ragged: from the City at War series. Splinter staggering around, looking unhealthy. (Jim Lawson)
Captive: From the comic book adaptation of the first movie. Splinter chatting with Danny while he's being held captive. (Jim Lawson)
Meditating: This one is pretty much self-explainitory. (Ken Mitchroney)
Unconscious: He got KO'd by Shredder, and still makes a fashion statement.
Talking: He looks kinda like someone took a flash picture and he blinked.
Leaping: Attack-Rat mode!
Whammy: Splinter puts on the "mental-whammy". This is why we love him. (Rick Veitch)
Panels: a panel sequence. I don't really remember what's going on in this one.
Gazing: I wanted this screengrab just 'cause...well, for some reason, Splinter just looks really rat-ish to me in this scene. So, there he is. Looking rattish. Heh. Get it? Rattish? Like Radish? God, I need to get off coffee...