Irina in the reboot and Sasha in the original versions of Rasputin Catamite speak in third-person for completely different reasons. Irina does so because she's cute and insane. Sasha does so out of sarcasm and to fake being a submissive out of laziness and to indulge in his masochistic tendencies.
Magellan has The Man Who Can, who is very particular about his name.
Ed from Digger refers to himself in this way, due to having had no company for many years, and having his name 'eaten' as punishment for a crime. Before Digger gave him his new name, he referred to himself as 'it'.
Karin-dou 4koma: Shizuki speaks this way in both child and adult mode despite being over 300 years old.
In the My Little Pony: Friendship Is Magic webcomic "Friendship is Tragic," which doesn't have its own webpage but can be found on deviantART, Moondancer speaks this way, to the point that once she actually tried to say "me" but found that she literally couldn't. note Moondancer is actually based on the background pony in the series that resembles Moondancer from the G1 My Little Pony TV Specials but was eventually named Twinkleshine in the toyline. In the very first episode, the then-unnamed Twinkleshine asked Twilight if she was coming to Moondancer's party; the comic's interpretation is that she herself was Moondancer and talking in a manner similar to a certain "great and powerful" stage magician (yes, Moondancer and Trixie eventually met, and it's as hilarious as you'd expect.) Once Twinkleshine got her name, there have been a few moments of Moondancer being mistaken for someone named Twinkleshine.
Devin of White Dark Life has a poor grasp on speech, and thus, literally has no idea what "I" means.