CREATE TABLE table_203_875 (id DECIMAL, "#" DECIMAL, "name" TEXT, "birth and death" TEXT, "office started" TEXT, "office ended" TEXT)

who among iceland 's lutheran bishops has held the longest tenure to date ?
SELECT "name" FROM table_203_875 ORDER BY "office ended" - "office started" DESC LIMIT 1
SELECT "name" FROM "table_203_875" ORDER BY "office ended" - "office started" DESC NULLS LAST LIMIT 1