A guitar lick derived mainly from the pentatonic scale in the key of Am but draws on the 9th note B and omits the minor 3rd C. Or you could look as an E Minor Pentatonic scale over an A chord. I'm not expert on theory so I'll leave it open for discussion.Either way a basic rock guitar lick that is fun to play and I think sounds cool.
Today's guitar lick tries to emulate a keyboard sound on guitar. It's uses a volume pedal and outlines a basic melodic statement using octaves. It's a pretty basic melody but you could elaborate on this theme by employing a few techniques that are well suited to octaves such as slides and whammy bar manipulation.
A rock guitar riff straight from the 80's. Using two note chord shapes called diads. This style of riff was employed by a lot of 80's rock and metal bands across a wide variety of styles. Bands from Motley Crue to Iron Maiden and Metallica frequently used them. The most famous diad is the root/fifth "power chord" loved by rock guitar players everywhere. The use of diads in this idea revolves around the muted open a string as a pedal point. You can incorporate diads into a wide variety of musical settings by changing your guitar tone, muting and rhythm. Using techniques such as slides and hammer ons can also change the feel of the riff.
A classic rock muted guitar rhythm today. This progression alternates between two chord shapes and uses muting and hammer ons to add color to the rhythm. Try expanding on this to create your own progressions. This style of rhythm guitar playing originated with Curtis Mayfield and was perfected by Jimi Hendrix. Today it is employed by John Frusciante from the Chili Peppers on a lot of songs from 'Dani California' to 'Under the Bridge' and many more.
The rhythm style is rooted in soul and rhythm and blues that was played in the 60's on the 'Chitlin Circuit'. Jimi Hendrix in fact played this group of clubs and bars when he started his career during and just after his brief stint as a paratrooper.
This guitar lick is a pretty basic example. You can experiment with the amount of distortion and ornamentation to alter the effect of this rhythm technique and use this in anything from rock or funk to soul or blues playing.