In my character demo, I do the following accents/characters:
Silly British: whimsical, articulate, poetic, high-class, musical, educated
Gangster: rough, mobster, hoarse, dumb, dull-witted, Brooklyn, NY
Radio announcer: 1940's style, Walter Winchell, reporter, newscaster, rapid-fire banter, period journalist
Dad: embarrassed, well-intentioned, bumbling, humorous
Southern Guard: deep, slow, thick, forbidding, dark, Alabama/Georgia
Jewish Tailor: rhythmic, sing-song, light-hearted, store proprietor
Mexican: good-natured Latino storyteller, lovable, comedic, authentic Mexican accent and cadence (I'm from the Texas/Mexican border)
Nerd: nasal, pedantic, thorough, scientific, panicky, emotional
Villain: grand, precise, evil, sadistic, powerful, vengeful
German: broad, cartoony, stereotypical, oompah German
Eurotrash: emotional, passionate, dramatic, flambuoyant, Italianesque
Hick: uneducated, superstitious, gossipy, hillybilly, Texas/Appalachia
Hero: romantic, hopeful, determined, optimistic, brave
Monster: spooky, vampiric, ghostly, haunting, Bela-Lugosi-like