Seven men who have allegedly been involved in criminal acts on trains in Hampshire during the past five months are being sought by police.
One punched a man to the floor, who then narrowly avoided being struck by a train at St Denys station, Southampton.
A man who threw scalding coffee into a train guard's face is also wanted.
Another was told to stop smoking on board a train approaching Fareham station, then threatened to stab the staff member in the face with a knife.
Det Sgt Sarah White, of British Transport Police, said: "Detectives investigating each of these cases have made local inquiries, followed up numerous leads and circulated the images on police intelligence systems in a bid to identify these people, but to no avail so far.
"I am certain that someone will recognise the people pictured in the CCTV images and am calling on anyone who does, or the people themselves, to get in touch."