FACTBOX: Key facts about Zimbabwe's Tsvangirai

(Reuters) - Zimbabwean opposition leader Morgan Tsvangirai returned home on Saturday for an election runoff with President Robert Mugabe despite his party's fears he might be assassinated by government agents.

Below are some facts about Tsvangirai:

* Tsvangirai is a former union leader who has been a thorn in Mugabe's side for a decade as the head of the Movement for Democratic Change (MDC), the main opposition group.

* The son of a bricklayer, Tsvangirai was born in 1952 in central Zimbabwe.

* He worked in a mine to feed his family and cut his political teeth in the labor movement as a mine foreman.

* Tsvangirai helped found the MDC in 1999. Despite intimidation, it stunned the ruling party by winning 57 of 120 seats at stake in a 2000 parliamentary vote.

* Tsvangirai was acquitted of plotting to assassinate Mugabe and seize power before a 2002 presidential election.

* Mugabe's party won a crushing majority in a 2005 parliamentary election, which the MDC said was rigged.

* The MDC split in 2005 in a feud over how to tackle Mugabe. A splinter group accused Tsvangirai of behaving in a dictatorial fashion.

* Tsvangirai was arrested at an anti-Mugabe rally in 2007. He said he had been attacked at a police station. Critics said the incident helped revive his sagging political fortunes.

* The long-awaited second round follows the disputed 2008 presidential election in which official results showed Tsvangirai beat Mugabe, but not by enough votes to avoid a run-off.

(For full Reuters Africa coverage and to have your say on the top issues, visit: africa.reuters.com/ )

(Writing by David Cutler, London Editorial Reference Unit)