Odsonne Edouard has completed his £14m move to Crystal Palace, signing a four-year deal with the Premier League side.
And Celtic have signed striker Girogos Giakoumakis, Benfica winger Jota and Tottenham defender Cameron Carter-Vickers, the latter on two on loan.
Edouard netted 88 goals in 179 appearances for Celtic after joining from Paris St-Germain in 2017.
"Scoring goals in the Premier League may be the biggest challenge in my career," Edouard said.
"But I'm confident in myself and my team-mates to be successful."
The Frenchman formalised a move to Glasgow after an initial loan spell for a club record fee in excess of £8m in 2018, and won three Scottish Premiership titles and four domestic cups with Celtic.