Buddy Holly

Once Buddy started the larger package shows, he bought a Fender Bassman. 4 10" [4-10 inch speakers]. At 50 watts, it was a powerful amp for that time. It was designed initially for electric bass, but it didn’t take long for guitarists to fancy it. This amp could handle the size of the venues the Crickets were playing by this time, not to mention being capable of overpowering the enthusiastic crowds that greeted them at their live performances. Particular amps seemed to have been used on specific tours.

http://www.superoldies.com/buddyholly/equipment.html

Buddy Holly owned a Fender TV Front Pro amplifier, similar to the one owned by Norman Petty of Norman Petty Studio. According to Mike & Mike's Guitar Bar, both amplifiers shared almost identical electronics. Kenneth Broad, the curator of the Norman Petty estate, confirms the accuracy of this information.

Used by Holly earlier in his career

In the image from Alamy, Buddy Holly is pictured with a Fender Vintage 1950s Pro Combo Amp, likely a 5C5 or 5D5 model from 1953-54, identified by its wide panel design.

Holly briefly used Gibson (what appears to be GA-40) Les Paul amplifier in 1955. He bought the amp along with Les Paul Goldtop, although he later switched to Magnatone.