For reference, the rule on Critical Hits says (PHB, p. 196):
When you score a critical hit, you get to roll extra dice for the attack’s damage against the target. Roll all of the attack’s damage dice twice and add them together. Then add any relevant modifiers as normal. [...] If the attack involves other damage dice, such as from the rogue’s Sneak Attack feature, you roll those dice twice as well.
There are a number of creatures in the game which do a fixed amount of damage on a hit (rather than rolling a damage die). Do these attacks do extra damage on a critical hit?
One example is the Sprite:
Longsword. Melee Weapon Attack: +2 to hit, reach 5 ft., one target. Hit: 1 slashing damage.
Since no die is rolled, does the sprite deal 1 or 2 points of damage on a critical hit? Rules as Written based answers are preferred (and seem to support not doubling), but a developer ruling or statement would be much appreciated.