Welcome, udara sankalpa.
It's OK to end a sentence with a form of the verb TO BE:
 Do you know who I am?
 Do you know who your grandfather was?
 Do you know who the 43rd Prime Minister of England is/was?
The difference between present is and past was is reference.If it's about a fact, then use present tense ().
If it's about the past, then use past tense (, ).Does that help?