Wolverhampton Wanderers have signed experienced Newcastle United defender Mike Williamson for an undisclosed fee on an 18-month contract.
Williamson, 32, first joined Wolves in October on loan, but he was recalled by the Magpies last month.
He becomes Wolves' third new signing in less than 24 hours.
Odoffin has signed a two-and-a-half-year deal and will join Wolves' Under-21 squad.
Head coach Kenny Jackett also signed Poland's Michal Zyro at the start of the month, but after scoring three times following his arrival from Legia Warsaw, he is now sidelined for up to eight weeks with a calf injury, along with fellow long-term absentees Jordan Graham and Dave Edwards.
Busy January window for Kenny Jackett
During a busy January, Wolves have also signed Swindon winger Will Randall and Wales Under-19 international striker Aaron Collins, from League Two side Newport, both for the under-21 squad.
They also lost left-back Scott Golbourne, who returned to home town club Bristol City claiming that he had not been offered a new Wolves deal.
Stoke-born Williamson made 170 appearances for Newcastle in a 383-match career which started as a trainee under former Wolves boss Colin Lee at Torquay United in 2001.
But he played just two games in the League Cup this season for the Magpies under boss Steve McClaren.
In his five games on loan with Wolves, they conceded just three goals, but he was then recalled by Newcastle as cover, only to injure his hamstring on his return to St James' Park.
BBC WM's Mike Taylor
"After much patience - and some impatience - from supporters, Wolves are finally getting transfer business done in the final week of the window.
"Mike Williamson strengthened the defence in his loan spell, bringing the knowledge and experience clearly needed, despite the sterling efforts of young Ethan Ebanks-Landell in the meantime.
"Joe Mason is rather more in the manner of most Wolves signings in recent times, a young player seen as being on the rise.
"It's notable that Kenny Jackett says Mason is 'a natural to play behind the striker in my ideal 4-2-3-1 formation'. Therefore, he is ideal to deputise for the injured Dave Edwards for the time being at least. The next task must be to find another option to play in front of him."