The Zebra Puzzle
— Solution

Using the simple clues
From clue (9): House 1 = Norwegian
From clue (14): House 1 is at the edge, so it has only one neighbour (House 2).
House 2 = Blue
From clue (8): House 3 = Milk
From clues (4) and (5): “The green house is immediately on the left of the white house” and “The owner of the green house drinks coffee”
Possible green/white pairs are (1,2), (2,3), (3,4), (4,5).
But House 2 is blue, so it cannot be green. And House 3 drinks milk, so it cannot be green (Clue 5, green drinks coffee).
Therefore only (4,5) works:
House 4 = Green and drinks Coffee  House 5 = White
From clue (1): “The Italian lives in the red house”
Colors used so far: House 2 is blue; House 4 is green; House 5 is white.
So the remaining colors for Houses 1 and 3 are red and yellow.
House 1 is Norwegian, so it cannot be the Italian’s house.
Therefore: House 3 = Italian and Red  House 1 = Yellow
From clue (7): House 1 = Hockey
From clue (11): “The person who keeps a horse lives next to the one who plays hockey” The hockey player is in House 1, so only House 2 is “next to” it.
So House 2 = Horse
So far we have:
Drinks fixed: House 3 = Milk; House 4 = Coffee.
The remaining drinks for Houses 1, 2, 5 are Tea, Beer, Wine.
Nationalities fixed: House 1 = Norwegian; House 3 = Italian.
The remaining nationalities for Houses 2, 4, 5 are Dane, Swede, German.
Sport fixed: House 1 = Hockey.
The remaining sports for Houses 2, 3, 4, 5 are Tennis, Golf, Billiards, Football.
Animal fixed: House 2 = Horse.
Clue (12) “The man who plays billiards drinks beer” has only two possible cases:
Beer cannot be in House 3 (milk) or House 4 (coffee) so we have either
Answer 1. Beer and Billiards must be in House 2 and either Tea or Wine in House 5.
or
Answer 2. Beer and Billiards must be in House 5 and either Tea or Wine in House 2.

Beer and Billiards in House 2 (? and ?) and either Tea or Wine in House 5.
Clue (3): “The Dane drinks tea”
House 2 is Beer, so it cannot be Tea, therefore the Dane and Tea must be House 5.
Clue (13): “The German plays football”
We know House 2 is Billiards (already fixed), so House 2 cannot be German (German must play football). That would force the German to be in House 4 or House 5. But House 5 is Dane so House 5 cannot be German. Therefore House 4 would have to be German (and play football).
Clue (15): “The woman who plays tennis has a neighbour who drinks wine” The tennis player can only be in House 3 or House 5 (because House 1 is hockey, House 2 is billiards, and the German/football is elsewhere).
If tennis were in House 5, its only neighbour is House 4, but House 4 drinks coffee, not wine (impossible). So Tennis would have to be in House 3. But House 3’s neighbours are House 2 (beer) and House 4 (coffee), so neither neighbour drinks wine (also impossible).

Beer and Billiards must be in House 5 (? and ?) and either Tea or Wine in House 2. If House 5 is Beer, it cannot be Tea, so the Dane and Tea must be House 2.
House 2 = Dane and drinks Tea
House 5 = Billiards and drinks Beer
Clue (13): “The German plays football”
House 5 already plays billiards, so House 5 cannot be the German. So the German must be House 4 (or House 2), but House 2 is the Dane, so:
House 4 = German and plays Football
Use clue (2): “The Swede keeps dogs”
The only remaining nationality not used is Swede, so:
House 5 = Swede and Dogs

We have:
House 1 = Hockey  House 4 = Football  House 5 = Billiards
So Houses 2 and 3 must be the remaining two sports, Tennis and Golf.
Use Clue (6): “The person who plays golf keeps birds”
House 2 already has Horse, so it cannot be the Birds house.
Therefore: House 3 = Golf and Birds and that means
House 2 = Tennis
Use clue (15) again, now that Tennis is fixed: “The woman who plays tennis has a neighbour who drinks wine”
House 2 = Tennis, so its neighbours are Houses 1 and 3.
House 3 drinks milk, so it cannot be wine.
Therefore: House 1 = Wine
Use clue (10): “The woman who plays tennis lives next to the man who keeps cats”
House 2 = Tennis, so Cats are in House 1 or House 3.
But House 3 already has Birds, so: House 1 = Cats
So for Pets we have:
House 1 = Cats,  House 2 = Horse,  House 3 = Birds and House 5 = Dogs
So the only remaining pet is the Zebra, which must be:
House 4 = Zebra
So it is the German, living in House 4, the Green house, playing football and drinking coffee, who owns the Zebra!