codger
An old man who is grumpy, stubborn, or a bit odd.
A codger is an old man, especially one who seems grumpy, set in his ways, or a bit eccentric. The word usually carries a tone of gentle teasing rather than meanness. You might call your grandfather an old codger when he complains about modern music or insists on doing things exactly the way he's always done them.
The word often appears with “old” in front of it, as in old codger. Picture a retired man who yells at kids to get off his lawn, refuses to use a smartphone, and tells the same stories over and over. He might be perfectly nice underneath, but he's stubborn about his routines and suspicious of anything new.
Sometimes codger suggests a person who's become a little odd with age, like someone who wears the same hat every day or talks to his cat as if it were a person. It's the kind of word you might use affectionately about someone you know well, but it would be rude to call a stranger a codger to his face.