President of the Senate
The President of the Senate is a title often given to the presiding officer of a senate, and is the speaker of other assemblies.
The senate president often ranks high in a jurisdiction's succession for its top executive office: for example, the President of the Senate of Nigeria is second in line for succession to the presidency, after only the Vice President of the Republic, while in France, which has no vice president, the Senate President is first in line to succeed to the Presidential powers and duties.
Argentina
The Argentine Senate is presided over by the Vice-President of the Republic, currently Amado Boudou. This was a recent expansion of the Vice-President's powers introduced as part of the 1994 constitutional amendments (Constitution, Art. 57). The Vice-President may only cast a vote to break a tied Senate vote.
Australia
The President of the Australian Senate is a senator, traditionally a member of the governing party or coalition, elected by the Senate at the beginning of each parliament as the first item of business. They are assisted by a Deputy President who is traditionally a member of the largest opposition party. The current president is Stephen Parry, a Liberal senator from Tasmania, who has held the office since 7 July 2014.