The motorcyclist who died on Tuesday night in Radlett has been named as 28-year-old Joseph Paul.
Mr Paul, who lived in London, was driving a red Honda motorcycle at about 6.50pm when he crashed with a black Mercedes SLK close to North Medburn Farm on Watling Street.
The woman from Radlett driving the Mercedes is in a critical but stable condition.
The man from Watford who pulled two people away from the burning vehicles has now been released from hospital.
Hertfordshire Constabulary are appealing for witnesses. Investigating officer, PC Gareth Rees from the Road Crash Investigation Team, said: "Our thoughts are with the family and friends of the man who passed away.
"I am appealing for anyone who witnessed the events leading up to the collision, or who saw the collision take place, to contact police as soon as possible. Any information you provide could significantly help with our enquiries."
Anyone with information is asked to contact PC Rees by calling the non-emergency number 101.