Aktobe (Kazakh: Ақтөбе, romanized: Aqtöbe, pronounced [ɑqtɵbʲe] ^ⓘ; Russian: Актобе) is a major city located on the Ilek River in western Kazakhstan. It serves as the administrative center of the Aktobe Region and is an important cultural, economic, and industrial hub in the region. As of 2023, the city has a population of 560,820, making it the fourth-largest city in Kazakhstan and the largest in the western part of the country. It covers an expansive area of approximately 428.469 km² and is strategically located to serve as a regional center for trade and commerce.

Aktobe is known for its natural resources, with two significant water reservoirs, Aktobe and Sazdy, that provide essential water for the city and surrounding areas. The city's economy is strongly driven by industries such as coal mining, metallurgy, and the extraction and processing of oil and gas. These industries have contributed to Aktobe's growth, transforming it into a vital center for energy production and heavy industry in Kazakhstan.

Aktobe's infrastructure has developed alongside its industrial growth. It is well-connected by road and rail to other major cities in Kazakhstan and neighboring countries. The city is undergoing rapid urbanization, with plans for further expansion and development. The agglomeration of Aktobe, which includes surrounding settlements, is expected to grow significantly in the coming years, with a projected population of around 1.3 million people.

In addition to its industrial significance, Aktobe is a growing cultural center. It hosts a variety of cultural events, and its educational institutions, including universities and technical schools, contribute to the city's development as a center for higher learning and innovation. With its expanding population, diverse economy, and increasing infrastructure, Aktobe is poised to continue its growth and development in the years ahead.

The name Aktobe comes from Kazakh ақ 'white' and төбе 'hill'; the name refers to the heights on which the original 19th-century settlement was located. Until 1999, the city was officially known as Aktyubinsk (Russian: Актюбинск).

The territory of the modern-day Aktobe Region has seen the rise and fall of many Central Asian cultures and empires. The region figured prominently in the history of the Kazakh "Little Horde". The Kazakh warlord Eset Batyr based his campaigns against the Dzungars from this area. His mausoleum is located 35 km (22 mi) to the south of Aktobe city. Abulkhair Khan (1693–1748) was also based in this region.

In March 1869, a Russian military fort with a garrison of 300 was built at the confluence of the Kargala and Ilek rivers, along the Orenburg - Kazalinsk caravan route. From that period onward, Slavic settlers began to migrate to the region in order to farm, and very soon, neighbourhoods were built around the fort. In 1874 the fort was expanded in size, and streets were laid out to and from the fort's gate. In 1891 the settlement was labelled a district city, and officially named Aktyubinsk.

In the late 19th and early 20th centuries the settlement rapidly expanded in size. While the 1889 population was listed as 2,600, by 1909 the population had increased more than four times to 10,716 official residents. The physical characteristics of the city had developed as well, and by the turn of the century the city had two churches, a seminary, a Tatar mosque, a Russian-Kyrgyz boys' school and girls' school, a clinic, a bank, a post office, a city park, a cinema and two mills. The Trans-Aral Railway was extended through the city in 1901. In the years leading up to World War I, industry began to develop in the town, including the construction of an electric factory, a brick factory, and the establishment of an annual trade fair.