Castelu

{{Infobox Romanian subdivision

|type = commune

|county = Constanța

|official_name = Castelu

|subdivisions = Castelu, Nisipari

|image_skyline =

|image_caption =

|image_location =

|image_map = Castelu jud Constanta.jpg

|map_caption = Location in Constanța County

|image_shield =

|leader_name = Nicolae Anghel{{cite web |url=https://prezenta.roaep.ro/locale27092020/romania-pv-final |title=Results of the 2020 local elections |publisher=Central Electoral Bureau |access-date=15 June 2021 |df=dmy-all}}

|leader_term = 2020–2024

|leader_party = PMP

|coordinates = {{coord|44|15|N|28|20|E|region:RO_type:city_source:GNS-enwiki|display=inline,title}}

|elevation = 15

|elevation_min =

|elevation_max =

|area_total = 52.80

|population_as_of =

|population_total = auto

|population_footnotes =

|postal_code = 907040

|area_code = +40 x41

|website = {{url|http://www.primaria-castelu.ro}}

}}

Castelu is a commune in Constanța County, Northern Dobruja, Romania.

The commune includes two villages:

• Castelu (historical name: Chiostel, {{langx|tr|Köstel}})
• Nisipari (historical name: Caratai, {{langx|tr|Karatay}}, {{langx|de|Karatai}})

Castelu is located in the central part of the county, along the Danube–Black Sea Canal.