Former Scotland Under-21 Archer joins after being released from his Spurs contract this summer. The 22-year-old joined the Tottenham academy in 2009 after a spell at Charlton, and took in several loan spells as a young goalkeeper, including at the Den last season.
Archer didn't make an appearance for the Lions, but he did feature on the bench several times in the latter part of the season. Likewise at White Hart Lane, Archer never featured for the first team - though he did get plenty of football in loan spells at both Wycombe Wanderers and Northampton Town.
Martin is a 26-year-old left back that arrives after his contract with Gillingham expired. The defender also came through at White Hart Lane and featured for the England Under-17s side just over a decade ago, before being released by Spurs and signing up at Blackpool. He was there for a couple of years before switching to the Gills, where Martin spent five years accumulating 161 league appearances.
The Lions have yo-yoed between the Championship and League One for much of the last 20 years, and Millwall boss Neil Harris will be hoping the pair can help his side bounce straight back up at the first attempt, having spent five seasons in the second tier.