... is probably one of the dragons. Voltarmi is described as a 'very large dragon'. Of course, if you count Flowers, we've got the Hippie Sequoia, who must be pushing the limits.

As for the smallest physical agent... as firemagic said, Corolla is only six inches tall. There used to be at least one Peter Pan fairy, but she's long gone now. I can't think of anyone else in with a chance (though of course the non-physical agents could plausibly claim to be both largest and smallest), but I'd love to hear anyone else's suggestions.

hS

PS: Alternate answer: 'Whoever's wearing a huge or tiny disguise right now'. Jay and Acacia disguised themselves as Entwives...

Seaturtle’s agent Terabyte is an Artificial Intelligence who apparently doesn’t have a physical body. How would you measure its size?

Dr. Freedenberg’s secretary (who may not be considered to be an agent?) is a particularly intelligent shade of the colour blue. How big is it?

HG

Smallest is probably Sergio Turbo's Agent Corolla.