Pope Francis, who died Monday aged 88, will go down in history as a radical pontiff, a champion of underdogs who forged a more compassionate Catholic Church while stopping short of overhauling centuries-old dogma.

Dubbed "the people's Pope," the Argentine pontiff loved being among his flock and was popular with the faithful, though he faced bitter opposition from traditionalists within the church.

The first pope from the Americas and the Southern Hemisphere, he staunchly defended the most disadvantaged, from migrants to communities battered by climate change, which he warned was a crisis caused by humankind.