The Beatles 

Few artists have come close to replicating the massive success of The Beatles.
Bizarrely as Solo Musicians they are amongst the few.
If you count the individual hits of  John, Paul, George and Ringo as if they were a still together they would be the 4th biggest selling artist behind The Beatles, Elvis Presley and Michael Jackson

John 
Lennon
John began his solo career even before the Beatles split in 1970. Cold Turkey and Instant Karma were released whilst still a Beatle. A series of hits followed though his biggest song wasn't released in the UK until 4 years after its release on  the Album of the same name...Imagine. It wasn't until 5 years later that it reached the number 0ne spot, unfortunately this was released as a result of his senseless murder in 1980. (Just like) Starting Over and Woman also topped the charts at this time. Happy Xmas War is Over has appeared 5 times in UK charts

John had 23 UK top 40 hits (including reissues) 11 of which were top 10 including 3 Number Ones

George 
Harrison
George was the first Beatle to have a solo number one with My Sweet Lord (it reached the top spot again 31 years later after George lost his battle with cancer)
His epic "All Things Must Pass" was the biggest selling album by any other former fabs.
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George had 11 top 40 hit UK singles 6 of which were top 10 My Sweet Lord topping the chart twice

Paul 
McCartney
 Paul is commercially the most successful of the former fabs, not only in beating his former colleagues but all other artists, having spent a total of 93 weeks at the top of the UK charts. A feat made even more remarkable when you know that he is the only artist to reach number one as a solo act, as part of a duo, a trio, a quartet a sextet and also as part of a nine piece line up.
Mull of Kintyre remains the biggest selling non charity single in the UK (Bohemian Rhapsody was a charity single on the second occasion it reached Number One). With this one song Paul outsold even the biggest Beatles hits.

Paul has had 67 UK top 40 singles of which 21 were top 10 including 3 Number ones (Wings, with Stevie Wonder and Solo)

Ringo 
Starr
Ringo was never really expected to have a solo career but released a string of hit singles, Back off Boogaloo and It Dont Come Easy were released prior to his 1973 "Ringo" album which featured all of his former colleagues (though on different tracks) and produced two hit singles

Ringo has had 5 top 40 UK hits of which 4 were top 10