It's wrong to stereotype but there are definate types that crop-up in my experience:
The superfit young hiker girl from NZ who just walked the Pacific Crest Trail then Via de la Plata and went back to the start of the primitivo "to have a go at that too" at 45km a day.
The bestfriends, one kitted out with all the best top of the range gear suffering badly and moaning who convinced their reluctant unfit friend to accompany them on camino, the friend in sneakers and jeans - is thriving.
The nice guy walking on an extreme budget who everyone helps out and who miraculously finds the funds for a detour to Madrid and back to see a concert.
The person who refuses to be passed and speeds up (usually complains about the speedwalker fit enough to catch-up but not fit enough to pass).
The cyclists who are still asleep when you leave, who you find in the albergue at end of that day asleep yet again.
The Korean lady who walks at 2.5km/h, never ever stops, (carries a white plastic carrier bag, wears full weather gear and a scarf even tho it's 28 degrees) and always arrives at next town at the same time as everyone else.
The guy boasting about how he started in Paris (to the person who started in Jerusalem).
Those with a heavy load that's not in their backpack, who you wish you could help but can't ask, they in turn are unwilling or unable to say what it is.
Walkers with all the best gear, clean unworn gear, they smell of fabric conditioner, like to walk 7-abreast on paths, shout and sing (species often found west of Sarria).
Smelly walkers with worn gear who are super fit and jog past groups after Sarria. (species roams the central plain).
The guy who's done every camino twice and will advise you of the quickest way out of town bypassing all the sights and monuments.
The badly out of shape person who pops up ahead of you fresh as a daisy with dry gear after a wet 32km day, who, when you casually and sincerely mention that taking the bus today was a really good move, insists they walked the whole way.
American Mom and daughter/son combos. Never Dad.
Those with lots more motivation than basic fitness (most frequent at early stages of camino). Usually have good gear and in very high spirits. Sometimes works out ok.
That guy from the balkans who gets along with everyone.
The Irish, getting closer to Santiago one short holiday break at a time (I blame Ryannair).
Love 'em.
Gap year students.
The person who suffers/benefits from an intervention from their group of new found friends (usually just before major city so 10kg of their gear can be shipped forward to santiago).
Ultralite/light pack walkers without guidebooks (me). Always looking out for Germans to ask for info.
The old school ex-military guy who's pack is 30kg and proud of it.
That grey-haired old lady who looks out serenely over a vista oblivious to anyone else, maybe with a tear in her eye...