One real, one imagined, two staged for artistic purposes.
- The Alexander Graham Bell and Mabel one is from here.
- Andy Warhol made Kiss, a 50-film in which all you see are different couples kissing, in 1963.
- Marina Abramovic and Ulay’s “Breathing In/Breathing Out” was performed in 1977 (I think).
- I’ve no idea who made the “JohnLock” image, but excellent use of Photoshop there. If you know who made it, do tell and I will happily put a line of credit in.