The varieties of non-vegetarian items made and eaten in Northern India is very large. A complete listing could fill pages and still remain incomplete. But in general we can say that people make eat flesh of many different types including chicken, mutton, pork, beef and fish. However, mutton and chicken are much more common as compared to others. Among these two also chicken, in general is liked more than mutton.
The most well known dish among non-Indians is perhaps 'tandoori chicken', which is a chicken grilled in a special type of oven called 'tandoor'. Then there are many different types of kebabs, or grilled food. 'Murg musallam' is delicacy chicken preparation which is cooked with gravy and is cooked so that it becomes very soft. The word "murg' in the dish indicates that it is made from flesh of a hen (or a cock). Chicken curry and mutton curry are perhaps the dishes made most commonly in homes.
Another common class of dishes, called 'pulao' are preparations of boiled rice with other ingredients added to it. Like kebabs these are many different kind of pulaos A special class of pulao, called 'biryani' originated in south India, but is now popular all over India.
'Samosa' is a snack food, and as explained in answer posted above it is made from different types of vegetarian and non-vegetarian fillings. The most common non-vegetarian filling is minced mutton, and is called 'mutton samosa'.
In view of the answer posted above, it will not be out of place for me to clarify that 'motichoor ladoo (or laddoo)' is a sweet made of gram flour. It is not a non-vegeterian dish. Also, I have not come across non-vegetarian 'chaat'. However this name is used for a very wide range of savoury and spicy snacks, and it is not all that difficult to think of some items of chaat with non-vegetarian ingredients.