In general, yes. It's a real person's name, so as long as your poem isn't copying the lyrics of The Beatles' song then there should not be an issue.
However, you should probably avoid it, because it's the title of a famous song by the Beatles and that's all anyone will think of when they read it.
Yes, you can use the name "Eleanor Rigby" in a poem since it is a fictional character created by The Beatles in their song of the same name. Just be mindful of the context in which you use it to avoid any potential copyright issues.
When Paul McCartney first started work on "Eleanor Rigby", it was as "Miss Daisy Hawkins". "Eleanor Rigby" was a song he was not happy with, he would do a little work on it, and put it away, and then do some more to it later on. Paul recalls that the name "Miss Daisy Hawkins" did not suit the song and that he may have picked the name "Eleanor" from working with Eleanor Bron on the movie "Help!" or, alternatively, he saw the name Eleanor Bygraves on a gravestone. Later on a trip to Bristol, he saw the name of a wine merchant on a shop window, Rigby & Evens Ltd. The evolution of the name was complete, and he had his suitably named character and song title.
The Beatles' U.K. single of Yellow Submarine was backed by Eleanor Rigby on it's B-Side.Yellow Submarine/Eleanor Rigby was the 13th Beatles single on EMI/Parlophone, released in the U.K. on 5 August 1966 with the catalog number R 5493.Yellow Submarine was recorded at EMI's Abbey Road Studios on 26 May 1966 in five takes. Eleanor Rigby was recorded on 28 April 1966 in fifteen takes.Yellow Submarine hit #1 in Britain and #2 in the United States and remained charted for thirteen weeks. Eleanor Rigby would go to #1 and stay at the top spot for four weeks in August and September of 1966.
Eleanor Tomlinson's birth name is Eleanor May Tomlinson.
You may be thinking of "Eleanor Rigby", who was hardly a girl, but an older lady who'd had a lonely life. (The other person in the song, Father McKenzie, was lonely also, but the two never met in life; he conducted her funeral service, which nobody attended.)
Brad Rigby was born May 14, 1973, in Milwaukee, WI, USA.
Lee Rigby died on May 22, 2013, in Woolwich, London, England, UK of murdered.
The Faerie Queen by Edmund Spenser from the time of Shakespeare may be the poem you are thinking of.
Eleanor Capaldi was born on May 20, 1985, in Glasgow, Scotland, UK.
Eleanor Fredericks was born on May 3, 1898, in New Britain, Connecticut, USA.
Eleanor Morra died on May 24, 1974, in Los Angeles, California, USA.
Eleanor Mendes was born on May 30, 1975, in Dar Es Salaam, Tanzania.
Ashlee Ashby was born on May 2, 1982, in Rigby, Idaho, USA.