Les was a classic. And the man could play. I liked him - first met him in the 70s, when his friend and longtime soundman Tommy Doyle was winding me my first-ever set of bespoke pickups. Les' contributions to music are undeniable, including being one of the early advocates for solidbody electric guitars, a pioneer of tape speed manipulation & "sound on sound" overdubbing and even more importantly, co-designer of the first multitrack tape recorder. In his sound-on-sound days he also discovered/created the flanging effect.
Many feel it was entirely due to Les' creativity that studio production first began to become essentially an instrument in itself. Bing Crosby bankrolled his home studio and many famous artists came to record in his Hollywood garage because he could produce a sound that nobody else could.
He was a genuine inventor with many, many patents - including the first headless guitar, with tuners below the bridge. Unfortunately his version was aluminum and wouldn't stay in tune when warmed by stage lights. (I had a headless aluminum-necked Kramer in the 80s that had the same problem.)
Les pitched the idea of a solid body model to Gibson in the 1940s and was rejected. It was only when Leo Fender's bolt-on solidbodies began selling well in the early 50s that the Gibson management decided they'd better offer a solidbody of their own.
By that time Les had become a best-selling recording artist in his own right, rather than just a sideman. (And he'd built his own solid body, "the log," working after hours at the Epiphone factory. He used that guitar for recording for many years even while he was using the Gibson for his live shows.) So he was offered an endorsement deal and lent his face and name to the Gibson model.
Still, I think it's only fair to point out that it was Ted McCarty who created the iconic guitar that bears Les' name. Les fine-tuned the original bridge & tailpiece designs along with the neck alignment, which improved the playability significantly. Les was an inveterate tinkerer and IMO something of a mechanical genius. He also insisted it had to be a classy looking instrument and was entirely responsible for the iconic gold top color scheme and the "black tuxedo" style of the Custom model when it came out.
Les was furious when Gibson changed to the thin double-cutaway guitar that later became known as the SG. They didn't even have the decency to tell him about it; his first encounter with the new guitar was seeing one for sale in a music store window - with his name on it. Discussing that was the only time I ever saw him genuinely angry. He hated that design, partly because he thought it had odd balance and a too-weak neck joint, but I think mostly because for him it was forever associated with the insult.