Carmine Caridi, who played Carmine Rosato in GFII has died.

The obit linked below has some interesting tidbits, including that FFC wanted Caridi to play Sonny, but Robert Evans over-ruled him.

Caridi also played Volpe (the Don whose coat gets stuck in the door during the helicopter attack) in GFIII.

What other actors had speaking roles as different characters in the Trilogy? (Sofia Coppola doesn't count.)

Carmine Caridi Dies at 85

None, Sivero who played Genco in GF2, also played a bystander in GF but no speaking lines in that one. Caridi I remember had something to do with Majestic River, then reading his bio realized that it was that Copy Right infringement, where he was kick out of Ampas.

Sofia played Michael Francis Rizzi in GF, but all she did was wail. She also played Mary in II but didn't say anything.

I didn't know Sofia played Mary in II she looked older than Sofia's two years

Sofia Coppola – Biography – IMDb

She was one of the cast members who were involved in all three of The Godfather films, along with Al Pacino.

She played as the christened baby in The Godfather (1972),
as a child on a steamboat in The Godfather: Part II (1974),
and eventually as Mary Corleone in The Godfather: Part III (1990)

Are you sure she played little Mary? I though she was one of the girls on the boat in the flashback scenes.

Sonny, I believe she appears twice in GF II: once as the child on the boat, once as young Mary. Here's the Wiki entry:

The Godfather Part II
Mary first appears in The Godfather Part II as the youngest child of Michael and Kay. She is a young child (aged about 4 or 5) in the late 1950s. Like Anthony, she does not have a significant role or story arc in the film.

Unlike James Gounaris, who played young Anthony, she's not listed in the credits.

Sophia Coppola was a toddler by the time of GFII, the young Mary seen playing in the hall way during the fight between Michael and Kay strikes me as being a few years older.

I think you're right, Sonny: She was only three years old in '74, when GFII was filmed.

That part always annoys me.