the face matches your sig
– Omnivore - Piers Anthony - 1968 novel Ballantine Books - First HC Edn. SFBC VG++ | eBay
Cover artist unknown
Re forum sigs, a lot of these would work

White Mountains cover art by Roger Payne; others unknown
– https://www.reddit.com/r/badscificovers/comments/vz12ad/the_city_of_gold_and_lead_john_christopher_knight/
– The City of Gold and Lead (Beaver Books) by Christopher, John: Very Good paperback (1977) | HALCYON BOOKS
– [April 16, 1968] Tripods and Others (April 1968 Galactoscope) - Galactic Journey
The Hobbit - 1979 Bulgarian edition - illustrated by Peter Chuklev
– Bulgarian Hobbit Edition
The Snowman by Vladimir Zelengorov (Vladimir Ivanov Simeonov)
Bulgarian, 1966 (Google Translate)
Cover illustration by Rumen Skorchev
– Владимир Зеленгоров — Снежният човек — Библиоман
One of the few books I still have so I was able to scan it myself:
Cover illustration by John Tenniel, yep
Cover illustration by Pauline Baynes
– A Dictionary of Chivalry cover by Pauline Baynes from Pauline Baynes
– https://archive.org/details/dictionaryofchiv00uden/page/n31/mode/2up
– INSPIRATIONS FROM THE BOOKSHELF C S Lewis - Words&Pictures
The Hobbit - 1975 Bulgarian edition - cover illustration by Peter Chuklev
– Джон Р. Р. Толкин — Билбо Бегинс или дотам и обратно — Моята библиотека
– Babel Hobbits - Gallery of illustrated, multilingual editions of The Hobbit by J.R.R. Tolkien
– 1975 FIRST – Hobbithunter
Cover illustration by John Schoenherr
Cover illustration by Richard Powers
– https://www.etsy.com/listing/1811415246/men-without-bones-and-other-stories-1962
– Publication: Men Without Bones
1970s covers by “O’Brien” (per ISFDB)
– The PorPor Books Blog: SF and Fantasy Books 1968 - 1988: Book Review: The New Tomorrows
– Agent of Chaos by Norman Spinrad - Modern Promotions - Paperback | eBay
Oh yeah also this other 1970s Agent of Chaos cover by an unknown illustrator: