Short answers, pulled from the story.
Catherine I of Russia was born Marta Helena Skowrońska in Swedish Livonia and rose from servitude to become the second wife of Peter the Great. After his death she was proclaimed Empress of Russia, ruling until her own death in 1727.
Catherine I became Empress of Russia in 1725, after Peter the Great died on the 28th of January 1725 without naming a successor. A coup arranged by Alexander Menshikov led the guards regiments, among whom she was very popular, to proclaim her ruler.
Catherine I of Russia began as a servant in the household of Pastor Johann Ernst Glück in Marienburg, Swedish Livonia. After Russian forces captured the town she passed into the service of Field Marshal Boris Sheremetev, then Alexander Menshikov, before becoming the mistress and later the wife of Tsar Peter I.
Catherine and Peter became estranged the year before his death over her support for her secretary, Willem Mons, and his sister Matryona, who had been selling their influence for access to Catherine and Peter. Peter had Willem Mons executed and exiled Matryona, and the couple did not speak for several months.
Catherine I of Russia died on the 17th of May 1727 at age 43, after catching a chill following a blessing of the ice ceremony on the river Neva in January 1727. Doctors attributed her death to tuberculosis, diagnosed at the time as an abscess of the lungs.
As Empress, Catherine I reduced Russia's military spending, which at the time consumed roughly 65 percent of the government's annual revenue. The resulting tax relief on the peasantry earned her a reputation as a just and fair ruler, though advisers otherwise controlled most of her reign.