Hammersmith and city hasn't got any stations served only by itself but it still runs from hammersmith (with circle line) to barking (with district line)
TfL's official position is that the Elizabeth line isn't a London Underground line (for reasons that I find unconvincing). https://www.standard.co.uk/news/london/crossrail-elizabeth-line-tube-tfl-london-underground-b1001058.html