Bromance is a sociological concept describing close relationships that form between two or more men. They have become increasingly common through the nineties and noughties, and have been popularised by characters such as Scrubs’ Turk and JD.
Something similar to bromance was first described by Aristotle around 300BCE who described the participants in a bromance as "those who desire the good of their friends for the friends' sake that are most truly friends, because each loves the other for what he is, and not for any incidental quality" presumably shortly before he took another huge draw on a bong.
Bromance: Ancient Greek style
Unfortunately, due to a greater intolerance (and general prudishness) towards male-male relationships for fear of being called gay, bromance fell out of favour until the 1970s, with the advent of the buddy film.
Whilst any genuine affection between the bromancers was thinly veiled behind acerbic humour and wisecracks (a tradition which continues today in shows such as House MD), the bromance film truly blossomed with the Hollywood 'frat pack', and its most famous disciples Ben Stiller and Owen Wilson. This convention has continued more recently with Judd Apatow produced films (which have included members of the frat pack), which typically contain male friendship as one of the main themes.
Friends- Joey and Chandler: Whilst there were 3 men in the friendship group of friends, there is no question that the real bromance was between Joey and Chandler. They even kissed once on New Year's Eve.
Scrubs- Turk and JD: The bromance that made us all believe in bromances, throughout the 8 series in which the focus was on JD, Turk has always been there with Carla in the background, voicing her concerns that they're going to run away together. Turk and JD were also responsible for the seminal bromance song "Guy Love".
How I Met Your Mother- Ted, Marshall and Barney: Notable because of the three-way nature of this bromance, often the plot of an individual episode will centre around two of the three characters.
House MD- House and Wilson: Whilst not as openly warm with each other as the other bromances listed here, the relationship between House and Wilson is similar to that of an old married couple- they bicker and undermine each other regularly. And although neither party are capable of maintaining a healthy relationship with a woman, they always have their unhealthy relationship with each other to fall back on.
The Frat Pack- Ben Stiller, Owen Wilson, Vince Vaughan and crew, starred in some of the most well known bromances produced in the early 2000s. The most notable bromance within the frat pack is that of Ben Stiller and Owen Wilson, who feature as main characters (and bromancers) in Zoolander and Starsky and Hutch. Whilst appearing in an additional 7 films together as smaller roles.
Judd Apatow films- Judd Apatow, a contributor in a number of frat pack films appears to have learned something about the importance of bromance. Many of his films- both as a writer and producer- have two or more male protagonists and the films typically examine their relationships as much as any other male-female relationship.
I Love You, Man- Starring Jason Segel and Paul Rudd (both stalwarts of Apatow films), this is pretty much the pinnacle of bromance films. The plot of I Love You, Man almost perfectly mirrors that of a typical romantic comedy. Only with men. In a completely heterosexual way.
Simon Pegg and Nick Frost- Bromances aren't just confined to American comedy; The British comedy duo behind Shaun of the Dead and Hot Fuzz (and the television series 'Spaced') are clearly advocates of bromance. Their upcoming film 'Paul' is to be a road movie about two British geeks in America, which will no doubt be swathed in bromance.