Spectra of F0v (top) and F5v (bottom) stars
Spectra of G0v (top) and G4v (bottom) stars
Spectra of K0v (top) and K5v (bottom) stars
Spectra of M0v (top) and M5v (bottom) stars
[No spectra yet]
T < 1300 K; very low-mass objects, not technically stars anymore because they are below the Hydrogen fusion limit (so-called "Brown Dwarfs"). Have cool Jupiter-like atmospheres strong in methane (CH4), water (H2O), and neutral potassium.
A stack of all of the spectral images showing how the spectral features change systematically from types O5v through M5v is shown on this page.
The spectra shown above are for real stars and run from 350nm to 740nm. I've taken digital scans of the spectra and "stretched" them into black-and-white images to mimic the photographic spectra used for many years for classification. The main difference between these images and photographic plates is that the latter did not generally extend as far into red wavelengths as modern CCD detectors. Putting two spectra close together like this shows clearly how the spectra change from the start to the middle of the class.
The line graph above shows the source spectra that went into each of the stretched versions. The original source spectra are from Jacoby, G.H., Hunter, D.A., & Christian, C.A. A Library of Stellar Spectra, 1984, ApJS, 56, 257.
The pictures of the stars are computer renderings of a glowing sphere with a color rendered approximately given its observed spectrum for that spectral type. The rendering was done by converting the spectrum into approximate computer RGB colors using the "CIE 1964 10-degree" color matching functions, using "sRGB" primaries and gamma function. The "white point" for the color conversion was set to the standard for sunlight (the "D65 white point"), hence a G2 star should appear white (with just a hint of yellow). Not guaranteed to be 100% real, but about as close as I figure I can get and still get the basic idea of stellar colors across that stellar colors are rather subtle because their emissions span the entire visible spectrum. The "limb darkening" effect you see is based on a simple empirical limb-darkening law for the Sun.