Council is the utmost authority in Mass Effect 1. An alliance of different races, members of each race represent their planet in the council. In Mass Effect 1 during the climax, there is a situation when as a commander you will be in a position to define its fate. You will have options to save the council or to let them die. The ending changes on that basis, you will have to pick a side of humans or council to conclude the game. Here is what happens in both the council choices in Mass Effect 1.
Should I Save the Council or Let them Die?
The fleet is under attack and as the commander, it is on you whom to help. Both the choices have different impacts on the ending, but there is no drastic change in the game.
Saving the Council:
If you go with this choice where you choose to save the council you will lose your beloved humans. The council will appreciate your concern about saving their lives and will offer commanders a chance to be a part of it. So the ending is quite ok and everyone gets something. But a lot of people are going to lose their life for the decision. If you want to earn the Council’s appreciation by sacrificing your fleet the go with this choice and get a space reserved in the authority. Commander picks Anderson to be part of the council.
Not Saving the Council:
The Ambassador is only left if you choose not to save the council. Being the commander you will be held responsible for the damage. However the hunger for power speaks, the ambassador will pitch for a new alliance with a human chairman. This means as the old council ends, a new council is formed ruled by humans. The Ambassador will give a positive pitch and ask you to pick a council chairman. Commander picks Anderson to be the chairman.
In both cases, whether you choose to save the council or not, Anderson will be appointed as the face of human leadership. Here you see there is no major impact on what is going to happen. The choice is yours, the commander anyhow lefts to deal with the incoming danger.