Use of 'Wa' in Japanese?

Question:

I know that 'Wa' is a topic marker, showing the topic of a sentence. Eg. Watashi wa Bob desu. But in all the examples I've seen the topic is always 'I'. I also know that the 'wa' can be left out is the topic is clear, but is it possible to have a topic which isn't I.
For example, 'You are late' Would you be a topic or a subject, and in what case could the topic be another noun or pronoun. Eg. 'Japan is great' Is Japan then a topic, not a subject.

Help is appreciated

Answer:

It's not so easy to read the question with no "?" marks.....

- "is it possible to have a topic which isn't 'I'?"
YES, for example, 'You are late' we often say "osokatta ne"
--> like when the subject kept his/her friend waiting. "anata osokattane" sounds like blaming.
Or a strict teacher would say "kimi chikoku da!" ('you' as a subject)

- in what case could the topic be another noun or pronoun?"
Eg. 'Japan is great' Is Japan then a topic, not a subject?
--> I would say 'Japan' is both a subject and a topic

note: we are taught that "the subject" in a sentence is always connected to a main verb.
Complicated enough, we also say "nihontte sugoi!" (Japan is great) without using "wa". But if you find this too confusing, pls just ignore this time.