Doorman is really DeMarr Davis. He was created by John Byrne and first appeared in Avengers West Coast #46 as a member of the Great Lakes Avengers. He was just a normal African-American young man till one day he found out that he could link to the Darkforce dimension and allow himself and others with him to pass through objects. He took on the name Doorman and answered Mr. Immortals call to start a superhero team. Doorman is the most cynical of the group as the team is always making mistakes that the other groups would not so he is always comparing them to the real Avengers. Doorman went into a deep depression as he felt responsible for the death of their newest member Grasshopper. The GLA was fighting Batroc the Leaper and one of his henchmen threw a sai at Doorman. Not realizing Grasshopper was behind him he used his powers to let the sai pass through him. It hit and killed Grasshopper.
During a battle with the super villain Malestrom Doorman himself died. In the afterlife he saw Grasshopper who told Doorman he forgave him. He also met the cosmic force Oblivion and using Doormans conncetion to the Darkforce was able to use Doorman as the new Angel of Death.
Doormans former teamates are still searching for their identity. They have potential to be a good team but so far are seen as jokes in the superhero community. The Avengers didn't want to be associated with them and since all the members are mutants they became the Great Lakes X-Men. They too requested the group change their name. They are now known as the Great Lakes Champions much to the ire of former Champions member and leader Hercules.
Recently Deadpool has been defeated by the Great Lakes Champions when he went after them for not registering with the Federal Government under the new Super-human Registration Act. Once he was stopped he was informed it was a mistake and they had already registered.
Also there was another character named Doorman who had his own book for Cult Press. It was really and anthology series with Doorman introducing stories of the macabre. You can get a look at the book and buy it if you click here. The link will take you to Mile High Comics.