The Eastenders character of Dennis Rickman is played by Nigel Harman. His mother Paula had an affair with Den Watts and Dennis was Den's son. The relationship between the two has been a highlight of the show since Den's return; the violent and unpredictable Dennis becomes almost puppylike when humoured by Den, who never hesitates to exploit Dennis's desperate need for a father in order to manipulate him.

Dennis's half sister is Vicki Fowler, while his true love is Sharon Watts; the adopted daughter of Den and Angie. Other flames include old friend and lover Kate Mitchell, her sister-in-law Sam Mitchell, Mitchell babysitter Joanne Ryan, Kat Slater and currently Zoe Slater.

East End ganglord Jack Dalton was Dennis's father figure but Dennis eventually murdered him in the woods following Dalton's admission that he had ordered the murder of Dennis's biological father, Den Watts. Despite this, Dennis remains friends with Dalton's second-in-command Andy Hunter and was even best man at his wedding to Sam Mitchell.

Dennis's first appearance was in handcuffs, as he was on day release from his prison sentence for GBH in order to attend his mother's funeral. His introduction as a full-time character was marked by his flooring of previous Square hardman Philip Mitchell with a single punch. This launched a rivalry with Phil which continued when Phil reneged on an agreement to meet Dennis for a fight at Phil's garage, The Arches, by bringing along several associates who gave Dennis a severe beating. Although Phil outwitted Dennis on this occasion, it can safely be assumed that Dennis had more fun; he infuriated Phil by seducing his wife, his sister and even his babysitter. The rivalry was concluded more successfully by Dennis's father Den, with the help of Dennis, upon his return to the Square. Den framed Mitchell for armed robbery by staging a break-in of a local factory, before trapping Mitchell inside the factory, leaving him with a handgun and the police on their way. Mitchell subsequently escaped from custody, and his attempt at retribution is likely to be a future plotline.

When he first arrived in Walford, he ran after some muggers who took Dot Cotton's handbag, and they remain friends. Dennis has speculated that Dot's mothering him has something to do with the established irredeemability of her own son, fellow bad boy and probable fellow murderer Nick.

Dennis is in charge of security at Angie's Den, the nightclub owned by the Watts family.