Brighton have signed defenders Martin Montoya from Valencia and Dan Burn from Wigan for undisclosed fees.
Both players have agreed four-year deals with the Seagulls, although Brighton have loaned Burn, 26, back to the Latics until 1 January.
Montoya, 27, has played for Barcelona and Inter Milan and represented Spain at Under-23 level.
He played 15 times as Barcelona won La Liga in 2012-13 and was also in their squad for their 2014-15 La Liga win.
"Martin's pedigree is excellent, and I'm delighted we have been able to add a player of his standing to our squad. There's no doubt he will improve our options in the right-back position," said Brighton boss Chris Hughton.
"He's won several domestic and European honours in Spain, and played the majority of his career in the top level of La Liga. He has a wealth of experience, at 27 years old he is a very good age, and I'm looking forward to working with him."
Burn, who is 6ft 7in, will return to Championship side Wigan until January as he recovers from an injury he sustained in pre-season.
"That benefits both Dan and ourselves as it will enable him to get fully up to speed in terms of fitness before January," said Hughton.
"He's an imposing figure and had an excellent season helping Wigan to the League One championship. He also impressed in an excellent FA Cup run to last season's quarter-finals."
Brighton have also signed midfielder Peter Gwargis from Swedish second-tier side Jonkopings Sodra IF for an undisclosed fee.
The 17-year-old has signed a three-year deal and will link up with the under-23 squad this season.
Gwargis scored three goals and assisted three in 17 first-team appearances last season and has three caps for Sweden Under-17s.
Brighton finished 15th in the Premier League last season and start their 2018-19 campaign with an away game at Watford on Saturday.
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