Carry That Weight is a song by The Beatles. Released on Abbey Road and part of the long, climactic medley that closes the album, it features vocals from all four of The Beatles (a rarity in their songs). It is preceded by "Golden Slumbers", and it segues into "The End".
The middle bridge, featuring brass instruments, electric guitar and vocals, reprises the beginning of "You Never Give Me Your Money", but with different lyrics. The ending also reprises the arpeggiated guitar motif from the end of that track, similar to the figure featured prominently in the George Harrison written tracks "Here Comes the Sun" and "Badge" (co-written by Harrison and Eric Clapton).
One interpretation is that the title (and main lyric) is a reference to two people, John Lennon and Paul McCartney. In McCartney's view, if Lennon allowed the Beatles to break up, he would be "carrying the weight" for that for the rest of his life. McCartney essentially blames Lennon and Yoko Ono for the decline in the band's relationship. The second reference, to McCartney himself, is about "carrying the weight" of the band by acting as the manager after the death of Brian Epstein. Until he took on the job, McCartney had never realized how much Epstein did for them, nor how difficult it was to manage the financial side of the Beatles. Similar sentiments are echoed in another of McCartney's Abbey Road songs, "You Never Give Me Your Money," and one line from "Oh! Darling".
In his book "Revolution in the Head", Ian McDonald interprets this lyric as an acknowledgement by the group that nothing they would do as individual artists in the future would ever equal what they had achieved together as The Beatles. In other words, that they would always carry the weight of their Beatle past. In the film Imagine: John Lennon, Lennon says that McCartney was "singing about all of us."