Nottingham Forest have signed PSV midfielder Ibrahim Sangare for a fee believed to be around £30m, and striker Divock Origi on loan from AC Milan.
Chelsea winger Callum Hudson-Odoi also joined for a fee of under £5m as Forest made seven signings on deadline day.
Midfielder Nicolas Dominguez signed from Bologna and goalkeeper Odysseas Vlachodimos has arrived from Benfica.
Defender Andrew Omobamidele joins from Norwich for £11m, while Arsenal full-back Nuno Tavares has signed on loan.
Ivory Coast international Sangare has penned a five-year deal and becomes the club's most-expensive signing, topping the initial £25m paid for Morgan Gibbs-White from Wolves in 2022, though that could eventually rise.
Forest have an option to make the loan of 28-year-old former Liverpool striker and Belgium international Origi permanent.
"Divock returns to the Premier League to further add strength to our squad," said Forest's chief football officer Ross Wilson. "We wanted to bolster our attacking options and Divock certainly helps us to do that."
Hudson-Odoi, who has three caps for England, signed a three-year deal after making 156 appearances for the Blues.
The 22-year-old spent last season on loan at Bayer Leverkusen, with Forest beating Fulham to the signing, having made a total of 156 appearances for Chelsea.
"It's massive for me to be here and I can't wait to get started. It's a new chapter for me," he said.
Hudson-Odoi spent 16 years at Chelsea but his career at Stamford Bridge never lived up to the early potential, and he last played for the Blues in March 2022.
Portuguese Tavares, 23, joined Arsenal from Benfica in an £8m deal in 2021 but now heads to the City Ground.
He spent last season on loan at Marseille, scoring six goals in 31 Ligue 1 games as OM finished third in the table.
"Forest is an historic club which won two European Cups and to be part of it makes me really happy," said Tavares.
"I'm really happy to stay in the Premier League as it's the best league in the world and I'm thankful to Forest for giving me that opportunity."
The new arrivals take Forest's summer signings up to 13, following the arrivals of Anthony Elanga, Matt Turner, Ola Aina, Andrey Santos, Gonzalo Montiel and Murillo.
Dominguez, who has played 11 times for Argentina, spent three-and-a-half years playing in Serie A for Bologna after moving from Velez Sarsfield.
The 25-year-old has signed a five-year deal while Forest's Swiss midfielder Remo Freuler went the opposite way to Bologna.
Dominguez said: "I watched the game Forest played against Sheffield United [a 2-1 win on 18 August]. I saw the fans in the stadium and it attracted me. I'm over the moon."
As Dominguez comes in, Freuler heads in the opposite direction to Bologna after barely a year in the Premier League.
The 31-year-old joined Forest from Atalanta in August 2022 and returns to Serie A perhaps sooner than intended.
Forest described the deal as permanent, while Bologna said it was a loan with an option to buy in the future.
Greece international Vlachodimos has signed a four-year deal which keeps him at Forest until at least the summer of 2027.
Vlachodimos was an ever-present for Benfica last season as they won their 38th Portuguese league title, and kept 21 clean sheets in 34 league appearances.
The 29-year-old has been capped 33 times for Greece and is expected to challenge Turner, who has started all four of Forest's games so far this season, to be the club's first-choice goalkeeper.
Forest's chief football officer Wilson said: "We are pleased to welcome Odysseas to Nottingham Forest.
"He is very talented and brings an abundance of experience with him, and he will add real competition to our goalkeeping department."