Doctor Who Poem by Ima Ryma

Doctor Who, a travelin' man
Through time landed in London town
In 1963 to span
Some decades to tamp evil down.
Shrouded in lots of mystery,
He developed a vast fan base,
'Whovians' followed him as he
Bounced all around from time and place,
Helping lots of good folks in need,
Rescuing them from baddie crime,
Just in the nick of time indeed,
And not change history in time.

Perhaps time travel some can do,
And if that is the case, then Who?