Celtic have signed Republic of Ireland midfielder James McCarthy and former England goalkeeper Joe Hart.
McCarthy, who has won 43 caps for Ireland, has penned a four-year contract following his summer exit from Crystal Palace while Hart joins from Tottenham on a three-year deal.
Celtic boss Ange Postecoglou will be hoping both players can have a positive impact on the squad after a difficult start to the season.
"To have signed for Celtic is a brilliant feeling and this is a special day for me and my family," said McCarthy.
"I know all about the club, the size of it and all the success it's enjoyed, particularly in recent years.
I’m looking forward to pulling on the Hoops, playing at Paradise and helping the team deliver more success to these amazing fans in the seasons ahead."
McCarthy, 30, returns to Scotland after 12 years in England with Wigan - where he won an FA Cup – Everton and Crystal Palace.
He began his career with Hamilton, where he made his first-team debut aged 15 in 2006.
Two-time Premier League winner Hart won 75 caps for England but struggled for first-team action in recent years while at Burnley and Spurs.
"This is a great moment for me in my career and I am absolutely delighted to be joining a club of Celtic's stature," said the 34-year-old.
"I know just how big this club is and of the incredible support that it enjoys, and I can’t wait to play in front of the fans at Celtic Park.
"I’m looking forward to meeting up with my new team-mates now and getting to work with the squad and, in particular, the other goalkeepers here."
Postecoglou added: "I’m delighted that we have signed two top-class players in Joe and James.
"Both of them have a wealth of experience at both club and international level, and that is something which can only benefit the squad, and I’m looking forward to working with both of them.
"I know our supporters will be well aware of both players, and I’m sure they’ll welcome them to the club and look forward to seeing both of them play for Celtic in the seasons ahead."
Postecoglou's side are preparing to face Czech club Jablonec in the first leg of their Europa League third qualifying round on Thursday.
Celtic have already been knocked out of the Champions League qualifiers by Danish side Midtjylland and lost 2-1 to Hearts at Tynecastle in their Premiership opener on Saturday.