Who is the current Chief Justice?
Washington Supreme Court
The Chief Justice is chosen by secret ballot by the Justices to serve a 4-year term. The current Chief Justice is Mary Fairhurst who was elected by her peers on November 3, 2016. Chief Justice Mary Fairhurst was sworn in on January 9, 2017, and succeeds Barbara Madsen, one of the longest-serving Chief Justices in Washington state history. 
Prior to January 1997 (pursuant to a Constitutional amendment adopted in 1995) the post of Chief Justice was held for a 2-year term by a justice who (i) was one of the Justices with 2 years left in their term, (ii) was the most senior in years of service of that cohort, and (iii) (generally) had not previously served as Chief Justice. The last Chief Justice under the rotation system, Barbara Durham was the architect of the present internal election system, and was the first to be elected under the new procedure, serving until her resignation in 1999.
Chief Justice of Kenya
In the event of a vacancy in the office of the Chief Justice, the Deputy Chief Justice performs the role in an acting capacity until a new Chief Justice is named. Where the Deputy Chief Justice position is also vacant, the senior-most Associate Justice of the Supreme Court will act as the President of the Supreme Court until a Chief Justice is named. An example of this occurred in 2016, when the senior Associate Justice Mohamed Ibrahim acted as the President of the Supreme Court following the early retirement of Chief Justice Willy Mutunga who turned 69 in June 2016, and the retirement of Deputy Chief Justice Kalpana Rawal who turned 70 in January 2016.