Motherwell have signed striker Jacob Blyth and defenders Ben Heneghan and Richard Tait after agreeing a new one-year deal with captain Keith Lasley.
Midfielder Lasley, 36, has been with the Premiership club since 2006.
Blyth, 23, ended last season on loan from Leicester City to Blackpool, scoring twice in eight appearances for the League One club.
Tait, 26, helped Grimsby win promotion to League Two and Heneghan, 22, was with National League rivals Chester.
Heneghan, who can play at right-back or centre-half, had been offered a new deal by Chester, who still hope to receive compensation.
English Championship clubs had also been interested in signing the England C international, who joined Chester in August 2014, initially on trial, following his release by Premier League side Stoke City.
Manager Mark McGhee told his club website: "In each situation, we had to battle hard against clubs on both sides of the border.
"Ben will come in and battle it out with Kieran Kennedy, Louis Laing and Stephen McManus for a centre-back position and Richard is an experienced and talented right-back who had a really strong season at Grimsby.
"Jacob gives us something we've not really got in attack, which is a big, powerful, strong centre-forward who will run in behind."
Blyth came through the youth ranks at Leicester but failed to make the first team with the English champions.
The Englishman had previous loans with Burton Albion, Notts County and Northampton Town then scored once in six appearances for League Two outfit Cambridge United before ending the season with Blackpool.
Galashiels-born Tait, who previously played for Nottingham Forest and Tamworth, joined Grimsby Town from Cambridge United last summer and helped his side defeat Forest Green Rovers in a play-off to return to the Football League.
Tait has signed a three-year contract, with the other two being given two-year deals and Blyth having a third-year option.
Lasley had been asked to take a pay cut but has now followed McManus and goalkeeper Craig Samson in extending his stay at Fir Park.
He will also continue assisting under-20s coach Stephen Craigan and take the under-17s along with McManus.
Lasley, who is in his second spell with Well, told the club website: "It has taken a bit of time, but I am really pleased we've managed to get a deal done and I am raring to go,"
"I've never made any secret of my feelings for this club; everything we've been through and enjoyed together over 15 or so years.
"It has been brilliant and I am sure there can be more good times to come."
Left-back Steven Hammell is still considering the reduced terms on offer at Fir Park, while forward Scott McDonald is considering whether to exercise the option of extending his contract.
McGhee added: "We've got other areas of the park we're looking to strengthen and will continue trying to nail our top targets."
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