According to the BBC, his death was confirmed by his daughter Katherine.
Character actor Wallach, who began his film career in 1956 after 10 years on stage, was admired for his wide range, in a career spanning six decades.
His portrayal of bandit chief Calvera in The Magnificent Seven was regarded by many as his definitive role.
Described as a "quintessential chameleon", he won an honorary Oscar in 2011.
Though he was never nominated for an Oscar during his 60-year career, the Academy rewarded him in 2011 for "effortlessly inhabiting a wide range of characters, while putting his inimitable stamp on every role".
His films included roles in the classic westerns How the West Was Won, The Misfits and The Good, the Bad and the Ugly.
Arguably best known for his villains, he made a lasting impression as Tuco opposite Clint Eastwood, in Sergio Leone's 1966 spaghetti western.
Years later, Wallach said strangers would recognise him and start whistling the distinctive theme tune.
The veteran star continued making films into his 90s, making his last big screen appearance in Wall Street: Money Never Sleeps in 2010.
Wallach was married to the actress Anne Jackson, with whom he often worked. In 1974 the two of them appeared with their two daughters in Saturday, Sunday, Monday.