Epic Riff: Several, especially "Crossroads", where his arragement is the most famous.
While the riff in "Layla" is definitely epic, that was Duane Allman, not Eric Clapton on the guitar. This leads people to mistakenly believe that ALL the great guitar playing on the album was Duane Allman, even on the three tracks on which he did not appear.
Face of the Band - Much as he tried to avoid this, Derek & the Dominos is best known for Eric Clapton. On the other hand, while Cream is best remembered as one of Clapton's bands, back in The Sixties all three members got equal attention. Bassist Jack Bruce was even the frontman.
Derek & the Dominos was in fact an attempt to avert this. When the song "Layla" appeared on the compilation album The History of Eric Clapton, sales shot up for the band's Layla and Other Assorted Love Songs...all because people realized Clapton played on the record.
Fan Dumb - Sometimes the case with people who worship his Bluesbreakers and Cream and perhaps Blind Faith tenures while despising his entire, varied solo career. They think that because he emphasized singing/songwriting over guitar playing, it meant that he never did long guitar solos again. A simple look at his live-- and some studio-- performances proves that notion wrong.
Growing the Beard - The first time he grew a full beard was in 1969 with Blind Faith, when was getting disillusioned with his "guitar hero" status. After the tour, he joined Blind Faith's little-known supporting act Delaney and Bonnie and Friends. The duo encouraged him to work on his singing and songwriting abilities. He became more than just a guitarist and more well-rounded as an artist. This led directly to his first self-titled album and a very successful solo career. In fact, the most well-known image of him is with a beard during the 1970's and 1980's rather than the baby-faced (or thin-mustachioed) kid from the Bluesbreakers and Cream.
Prior to that was the level of virtuosity and feel Clapton acquired between leaving The Yardbirds (where he was already well regarded as an impressive player) and the "Beano" album, which set the scene for the rest of Clapton's career.
Seinfeld Is Unfunny - Clapton is best known now for his unplugged solo material and his lighter pop hits, but back in the 60s he was an even more influential guitarist than Jimi Hendrix. This was even the guy who influenced Hendrix.
The image of a guitar hero playing a Gibson Les Paul through a Marshall amp arguably began with Eric.