Yes, there are a few stars in our Milky Way galaxy that are visible from other galaxies. The most notable example is the star known as V1 (Variable 1) in the Whirlpool Galaxy (M51). The Whirlpool Galaxy is located approximately 23 million light-years away from us, and V1 is a Cepheid variable star that can be seen within it.
Cepheid variable stars are used as standard candles in astronomy because their brightness pulsates in a regular and predictable manner. By observing the period of their brightness variations, astronomers can determine their intrinsic luminosity and use that information to calculate their distances.
The discovery of V1 in the Whirlpool Galaxy by Edwin Hubble in 1923 played a significant role in establishing the extragalactic nature of spiral nebulae, leading to the understanding that these objects are separate galaxies outside of our own Milky Way.
It's remarkable to think that we can observe individual stars in other galaxies despite the vast distances involved. This ability to study objects beyond our galaxy provides valuable insights into the nature of the universe and helps refine our understanding of its structure and evolution.