Maryan Shved has completed his move to Celtic from Karpaty Lviv and says it is "very emotional" to be the first Ukrainian to join the Glasgow club.
The 21-year-old winger, who has signed a four-and-a-half year contract, will remain with the Ukrainian Premier League club for the rest of the season.
"Playing games over the next few months is going to be huge for me so I can come here with confidence," he said.
Celtic have also signed Manny Perez and former Rangers trialist Andrew Gutman.
Both American defenders have signed three-and-a-half-year deals and as with Shved, Perez, 19, and Gutman, 22, will be loaned back to teams in the United States.
- Deadline day - deals, gossip and debate
- Brown signs new Celtic contract
- Sunderland sign Morgan on loan
Perez plays for North Carolina State University and is a USA Under-20 international. He had been training with the Scottish champions during December.
Indiana Hoosiers player Gutman won the Hermann Trophy, awarded annually to the best male and female college footballers in America, last year.
Shved returned to Karpaty in 2017 after a year with Sevilla's B team and scored eight goals in 18 appearances this season.
Karpaty sit eighth in the Ukrainian Premier League before the 12-team league splits into two - the top half competing for the title and the bottom half to avoid relegation.
"This stage of the season is also important for Karpaty Lviv, because they're fighting in the league, so they'll need me now more than ever and there's a personal weight on my shoulders to really perform," Shved added on Celtic's website.
Find all the latest football transfers on our dedicated page.