Japan international Suzuki, 23, joins for around £30m, arriving despite the collapse of Emiliano Martínez's proposed move to Juventus over the weekend after the two clubs could not agree a fee.
Martínez, who helped Villa win the Europa League in May and lifted the World Cup with Argentina in 2022, now faces an uncertain future at Villa Park following the failed switch. Villa regard Suzuki as their long-term No 1, potentially for the next decade, after two seasons at Parma in which he made 59 appearances and helped the Serie A side finish 13th.
Italy's Ruggeri, 24, arrives in a £17m deal to replace Lucas Digne, who completed his move to newly-crowned European champions Paris Saint-Germain on 9 August. A Europa League winner with Atalanta in 2024, Ruggeri made more than 100 appearances for the Bergamo club before joining Atletico Madrid last summer, and although called up to Italy's senior squad, is yet to earn a first cap at that level.
"I'm very excited and I'm very happy to be here to start my new journey," Suzuki told VillaTV. "I think this is the right club to start my first journey in the Premier League. And also they are always competing for trophies.
"I want to play at the highest level and that's why I've decided to come here."
Suzuki impressed at this summer's World Cup, starting all four of Japan's matches, and was on the winning side when his country beat England 1-0 at Wembley in March, a game settled by a goal from his new Premier League rival Kaoru Mitoma of Brighton. He becomes the first Japanese men's player to represent Villa, following in the footsteps of Mana Iwabuchi, Maya Hijikata and Akane Okuma, who have all played for the club's women's team.
"I'm so proud of that," Suzuki said of his landmark signing. "I want to make some history at this great club and I'm really looking forward to playing on the pitch. It was a great two seasons in Italy and also the World Cup as well, and my dream is to play in the Premier League. Now it is time for me to play in the Premier League. I want to prove myself at this highest level."
Both new arrivals are in contention to make their Villa debuts in Sunday's Premier League opener away to Brighton, as Unai Emery continues to reshape his squad following last season's Europa League triumph and fourth-placed league finish.