In Northern India there is a saying - "Ghar ke Baahar Naalaa, Deevaar mein Aalaa, and Ghar mein Saalaa are always dangerous". Its English translation is "An outlet of dirty water outside the house, a small empty place to keep some small things in a wall and the wife's brother (Maamaa) in the house - all three are dangerous." In many contexts it is true also. Here I will tell you about some Maamaa (mothers brother) who have been famous, here it is not necessary that they were living in the house or not, the important point is that they all were Maamaa.
The first name which comes to the mind is of Kans. Kans was King Ugrasen's son, Devakee's brother and thus Krishn's Maamaa. Everybody knows about what he did to his nephews. He loved his sister Devakee very much and he loved his friend Vasudev also very much, so he decided to marry Devakee to Vasudev. He did that and to show his love towards Devakee, he himself drove their chariot to their place from his palace. When he was driving the chariot, a Divine voice said - "To whom you are taking with so much love, her eighth child will be your killer." Hearing this Divine voice, he got so much upset that he got ready to kill Devakee at the same time drawing his sword. Vasudev was very intelligent. He pacified him saying many soothing words. He said - "It does not look nice for you to kill (1) your sister to whom you love so much, (2) She is a woman, it is not good for a Kshatriya of your caliber to kill a woman, (3) It is not good to kill a newly-wed girl, and lastly (4) It is only her eighth child, so there is still time, why to kill her now. You can take her eighth child, I myself will give you her eighth child, and you may do with him whatever you like."
Kans got agreed on the condition that Vasudev would give all his children to him. To make sure, and to keep track of each child he kept both of them in prison and asked his men to inform him about the birth of each child. Those people did that and he killed their 6 sons. Nobody knew about the 7th son as Bhagavaan's Yog Maayaa took the child out of the womb of Devakee and put it in the womb of Rohinee, another wife of Vasudev. But as soon as he heard the the eighth child is born, he immediately came to the prison and tried to kill him. But he was so surprised to see that it was not a son, but a daughter. He did not want to take any chance and he killed her also. As he hit her on the stone, she flew into the sky from his hands announcing that "Your killer has already been born, why do you want to kill me?"
Kans then ordered his people to kill all children born during the last couple of days. Pootanaa demoness did that, but still Krishn was not killed, rather He killed her. Kans sent many Raakshas to kill Krishn, but all his Raakshass were killed. In the last Kans was killed by Krishn.
The second names comes to mind is of Shakuni. Shakuni was the Prince of Gaandhaar country and when his sister Gaandhaaree was married to blind Dhritraashtra, he got very angry. At the same time he took a vow that he would destroy the whole family of Dhritraashtra. He also came to Hastinaapur and started living there. Thus Shakuni was the Maamaa of Kaurav - Duryodhan, Dushaasan etc brothers. He was the master mind of all the evil feats of Duryodhan. He never advised him properly, rather he always fanned the fire of his jealousy towards Paandav and in the end he became the cause of the destruction of the whole Kuru family.
From the very beginning, from mixing poison in Bheem's Kheer, planning to kill all Paandav in Laakshaa Griha, dividing the kingdom (in Hastinaapur and Khaandav Prasth), idea of playing Dice Game and then cheating in it while playing, then the second Dice game, exile of 13 years to Paandav including one year of living incognito, insulting Paandav by sending Durvaasaa Muni to them after their food time etc etc, all were his evil planning to get kingdom for Duryodhan. In the last he was killed by Sahadev.
The third Maamaa, Shalya was the King of Madra kingdom and he married his sister Maadree to King Paandu. Maadree had a twins, Nakul and Sahadev. Thus Shalya was Maamaa of Paandav. Shalya was very brave, a Mahaarathee. Keechak was also very brave, he had the strength of 10,000 elephants, so there were only four people who could kill Keechak - Bheeshm, Shalya, Balaraam and Bheem; and thus Shalya was one of them. It shows that he was equal to Bheeshm, or Balaraam or Bheem or Keechak. He was a very good charioteer too - Karn compared him with Krishn when he requested him to be his charioteer.
When it was decided that the war had to happen, both Kaurav and Paandav invited their people to join them. So Shalya should have joined Paandav being their Maamaa and with the same intention he set off on his journey. But with the cunning advice of Shakuni, Duryodhan made a very good arrangement of his rest areas at all appropriate points on his path and felicitated him with all kinds of comforts. Seeing all this arrangement Shalya was so happy that at all points where he stayed, he said to the servants that he would praise their services to the King. As per instructions of Duryodhan, his servants never said a word about those camps as who made that arrangement for him.
When Shalya arrived in Paandav's camp, he admired their arrangement. Yudhishthir said - "But we haven't made any arrangement." Shalya asked - "Then who made that arrangement? When I said that "I will give a good report of your good services to the King, then also they did not tell me anything. I did not know this that you have not made this arrangement, if I had known this I would have never stayed there. Now what should I do? I have accepted his food, I cannot leave him." Yudhishthir said - "Maamaa, You have been cheated. Duryodhan has played this trick to bring you on his side. I know that you cannot leave him now, but please promise us that you will always discourage Karn to fight with Arjun."
Shalya could not do anything else, but he did what Yudhishthir said to him. His own nephews, Nakul and Sahadev were so sad with this, that they said to him - "Maamaa, Today you made us the children of stepmother." In the end Yudhishthir killed him.