Most of these actors being proposed for Halt are way too thin and handsome. Someone's going to suggest Matthew Mcconaughey next! Of course my top pick is dead, so I guess I shouldn't complain. But for you young'uns out there, this is Oliver Reed:

Halt's description, as best I remember it, his beard is bushy, and his dark eyes are steady and unwavering. He has unkempt hair that looks as if he cut it himself with his knife. He looks grim and forboding, though he has a sarcastic sense of humor. Again, I give you Oliver Reed:

Reed stared in well over a hundred movies, and was a legendary drinker and ladies man. Not at all personally like Halt, he still looked like him, and more than had the acting chops to pull it off. A quote attributed to Reed:
"My only regret is that I didn't drink every pub dry and sleep with every woman on the planet."
His last movie was Gladiator, for which he was paid $1,000,000, and for which he cost the movie company an extra $3,000,000 because they had to CG his unfinished scenes when he died. He died of a heart attack in a bar after downing three bottles of Captain Morgan's Jamaica rum, eight bottles of German beer, numerous doubles of Famous Grouse whiskey and Hennessy cognac, and beating five much younger Royal Navy sailors at arm-wrestling. His bar bill for that final lunch time totaled 270 Maltese lira, almost £450. Reed once said: "Richard Burton was hitting the bottle with Jimmy Hurt the night before his death. He knew it was going to kill him, but he did not stop. I don't have a drink problem. But if that was the case and doctors told me I would have to stop, I'd like to think I would be brave enough to drink myself into the grave." And so he did.
Reed was a legend that could outdrink, outfight, and outact anyone. If you've never seen an Oliver Reed movie, do yourself a favor and pick one up. You won't be sorry. My personal suggestion? 1973's "The Three Musketeers" and it's followup "The Four Musketeers". (Christopher Lee is in those, as well as a veritable who's who of 1970's acting royalty.)
But no, sadly, we can't have Reed. Except in my head, and that's where it really counts, eh?