Allen is one of the most prolific artists in his field, having published more than 2,500 illustrations for hundreds of genre publications, including Isaac Asimov's SF magazine, "The Magazine of Fantasy & SF," "Cemetery Dance," "Whispers," "Fantasy Tales," "Weird Tales," "The Horror Show," "The Robert Bloch Companion," and many others.

Allen's art has been published since 1973, but he did not start to submit it to the professional markets until 1982, when his first professional sale was to Asimov's SF.

Allen is currently a member of The Association of Science Fiction and Fantasy Artists and has won numerous awards in the past. A couple of these include the L. Ron Hubbard Illustrators of the Future Award and for 8-10 years in a row, Allen won Best Artist  and other categories for the Small Press Writers and Artists Organization

A collection of his drawings will be published in the near future, with an introduction by Brian Lumley. Allen is a former U.S. Marine infantryman and a decorated Vietnam war veteran, including a Purple Heart; and he is a rabid collector of genre books and magazines, possessing nearly 20,000 items of the sort.

He is self-taught and prefers working with pen and ink, which allows him to create incredible detail. He has also just started to work in colors with wondrous results. Allen is married, has two children, and lives in Upper Darby, PA

Allen's art book, Travelers by Twilight, is now out of print from Magic Pen Press. 

The book is 84 pages long, paperback and has many illustrations in it seeing first publication. 

With a great introduction from Brian Lumley and an appreciation by Jason Van Hollander, this a great collection to have if you are a fan of Allen's work.