Nelson Mandela was an activist, political leader, and is the former president of South Africa. He also served as head of state, and served on the African National Congress for 6 years. He spent 27 years in prison, but was released right before a racial civil war almost broke out. Mandela had similar views to Gandhi such as spending time in prison, being involved in government issues, and using non-violent protest methods.
Gandhi was an activist, promoting freedom and equality. He believed in non-violence protests. One example of his work is the salt march, salt was taxed and they were not allowed to buy it without paying tax. So, they all marched down to the ocean, and took some salt. Gandhi was in jail for 27 years in total, but always seem to get out. He influenced so many people in ways you couldn't even imagine.
Martin Luther King Jr. and Gandhi both had similar views on how to gain freedom. They both used non-violent methods to get freedom for what they supported. They believed violence was not the answer, and used methods such as civil disobedience, jail time, and peaceful campaigns to obtain the freedom they desired.