Rotherham have signed Levski Sofia defender Aimen Belaid and free agent goalkeeper Alex Cairns.
Tunisia international Belaid, 27, can also play in midfield and has signed a two-and-a-half-year deal.
Cairns, 23, who has signed a deal until the end of the season, spent the first half of the season with League One Chesterfield.
Both players could feature in Saturday's FA Cup third-round tie against Yorkshire rivals Leeds United.
Find all the latest football transfers on our dedicated page.