1. He is master of the situation.
2. He is the master of the situation.
........
In dictionaries, I could see #1, not #2. Can't we use 'the' before 'master' here?
3. I met Father on the street.
4. I met father on the street.
5. I like Master very much.
6. I like master very much.
...........
I think #3 and #4 are correct. What about #5 and #6? Can we use 'master' like 'father'?
Both 1 and 2 are fine.
3 is fine if "Father" is referring to your own father.
4 is not fine, but would be if you wrote "the father" there. Then you'd be referring to someone else's father.
5 is fine if you're referring to someone by name or title..
6 is not fine, but would be if you wrote "the master" there. Then you'd be referring to someone's master in general.