|First seen||The Mysterious Mr. Friend|
Even though Mr. Friend was meant to be friendly toy and something for the kids to play with, he ultimately scares the babies.So much that Tommy and the other Rugrats spend an episode fighting to no ends to get rid of him, They succeed destroying one by pushing him over the fence boarder, allowing him to walk away on the streets, but unknowingly he accidentally started up the other Mr. Friends that Stu had made. This causes the babies increasingly horror, but rather than hide the babies go all out and do anything to destroy the toys. As they finally defeat the toys, Stu comes outside and looks in distress at how his inventions were destroyed.
Didi doesn't seem to be at all upset over the demise of the Mr. Friends, but she still tries to comfort Stu telling him that perhaps the world wasn't ready for Mr. Friend yet. She takes him back inside the house and encourages him to plan a better toy. While the babies believe there nightmare's are over for them, Angelica comes by and reveals she found a great toy. The toy turns out to be the Mr. friend that escaped from the Pickles house and which Angelica found walking down the street. The babies scream in horror and run away leaving Angelica confused but happy as she finds Mr. friend neat. It should be noted that the babies constantly mispronounce the name of the toy as "Mr. Fiend".
Mr. Friend appears in the Rugrats first video game "Rugrats: Search for Reptar" where he has his own level, The Mysterious Mr. Friend (Search for Reptar). In this level the player is in the Rugrats basement as Tommy, who actives Stu's toy machine which produces a Mr. Friend doll. The player much keep away from the doll whilst picking object off the floor and throwing them at the doll. After a couple of hits or kicks the doll is broken and the player wins round one. Round two is the same as round one except that the player has to go up against three Mr. friend dolls this time.