| Honorific-Prefix: | Admiral |
| Marcos Sampaio Olsen | |
| Office: | Commander of the Brazilian Navy |
| Term Start: | 5 January 2023 |
| President: | Luiz Inácio Lula da Silva |
| Minister: | José Múcio |
| Predecessor: | Almir Garnier Santos |
| Birth Date: | 8 March 1961 |
| Birth Place: | Ceará, Brazil |
| Allegiance: |  Brazil |
| Rank: | Admiral |
| Serviceyears: | 1979–present |
Marcos Sampaio Olsen (born 8 March 1961) is a Brazilian navy admiral, incumbent Brazilian Navy Commander. He joined the military career in 1979 and was declared Guard of the Navy in 1982. Olsen acted as commander of minesweeper NV Atalaia (M-17) and submarine S Tapajó and as chief mate of submarine S Tamoio and aircraft carrier NAe São Paulo.[1] [2]
In 2011, Olsen was promoted to counter admiral and assumed many offices in the Navy.[2] In December 2017, Olsen was responsible of the General Management of Nuclear and Technological Development of the Navy, responsible for planning and coordination of all activities related to the development of nuclear technology.[3]
On 30 December 2022, then Brazilian president Jair Bolsonaro nominated Olsen as Navy Commander, officialized on 5 January 2023 by president Luiz Inácio Lula da Silva.[4] [5]
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