A German woman, 51, has died of injuries sustained in the van attack in the Spanish city of Barcelona on 17 August, officials say.
Her death brings to 16 the number of people killed when Islamist militants struck in the city and the nearby town of Cambrils.
The attacks traumatised the region, Catalonia, six weeks before an outlawed referendum on independence from Spain.
King Felipe was booed when he joined a memorial march on Saturday.
A cell of 12 jihadists has been blamed for the attacks. Eight are dead, while four have appeared in court in Madrid.
Hospitals in Catalonia and Zaragoza are treating 24 other people for injuries, the Catalan health department says:
- The condition of five of those hurt in the Barcelona attack is critical; three are in a serious condition and 12 are in a less serious state
- One of those hurt in the Cambrils attack is in a serious condition, with three others in a less serious condition
The attacks began when a van mounted Barcelona's Ramblas boulevard, and the driver deliberately ran people down along the tree-lined path before fleeing the scene on foot, later stabbing another driver to death when he hijacked his car.
The attacker, Younes Abouyaaqoub, was tracked down by police west of Barcelona four days later and shot dead.
Also on 17 August, a car was driven into pedestrians in the popular seaside resort of Cambrils.
When the car overturned, five attackers climbed out, some of them wearing fake suicide bomb belts, and were shot dead by police.
Two other members of the cell, including its suspected ringleader, were killed in an explosion at a house apparently being used as a bomb factory, at Alcanar, further down the coast from Cambrils.
The blast occurred shortly before the vehicle attacks and may have spurred the cell's surviving members into action.
An estimated half a million people marched through Barcelona on Saturday in a gesture of defiance against the attacker, many using the slogan "I'm not afraid".
King Felipe VI joined the demonstrators, alongside Prime Minister Mariano Rajoy, causing some indignation among Catalan secessionists, a number of whom waved the lone-star flag of the Catalan independence movement.
Some protesters whistled and shouted "out" at the king.
Prime Minister Rajoy had encouraged "everyone" to take part to show that "Catalonia and the rest of Spain [are] united against terror".
The Catalan regional government is bent on holding a referendum on independence on 1 October - a move Mr Rajoy has vowed to resist.