The answer to this depends on which tradition of Buddhism is being discussed.
For example, the leader of Tibetan Buddhism (and perhaps the most respected Buddhist in the world) is the Dalai Lama.
In other Buddhist groups, the titles and positions vary widely, just as they do in Christian groups.
Buddhism has many sects and schools and so there is no single religious leader. Much as the pope may be regarded as a Christian leader, he is not the leader of all Christians.
Chela
There is no single leader of Buddhism any more than there is a single leader of Christianity , Islam or Judaism. Each group follows its own leader or traditions.
The Dharmapada
They could be called:* Rinpoche (Precious one)* Lama * Abbot (in charge of a lamasery) * Master * Shabdrung* Teacher (Sensi) * Brother * Tulku * Gelongma
called Imam
Tibetan Buddhism is Buddhism practiced in Tibet and the Himalayan region. There are many sects (Nyingma, Kagyü, Sakya and Gelu) each with their own leader and no overall leader. The current leader of the Gelug school, the newest of the schools of Tibetan Buddhism is the 14th Dalai Lama. He is perhaps the best known of these leaders.
An acolyte .
The Islamic religious leader is called the Imam, however in Islam God has said that everyone is equal and that their is no leader, the Imam is mainly used to teach people about the Islamic faith, and is also used to lead prayer, but he is not seen as a leader as everyone is seen as equal. The Religious founder in Islam is The Prophet Muhammad (PBUH).
a pope or priest is a religious leader
The founder is baddla and the leader well Buddhism don't feel have a leader
The collection of Vedict texts is called Upanishads. It includes the early central and religious concepts of Buddhism, Hinduism, and Jainism.