Elliptical galaxies are smooth, featureless blobs ranging from nearly spherical to elongated. They contain mostly old, red stars and very little gas or dust, meaning star formation has largely ceased. The largest galaxies in the universe are giant ellipticals — IC 1101 has a measured visible diameter of roughly 400,000 to 550,000 light-years, several times the width of the Milky Way. Its faint diffuse halo may extend even farther, possibly a few million light-years.

Ellipticals form primarily through galaxy mergers. When two spiral galaxies collide and merge, their organized disk structures are destroyed by gravitational chaos, scattering stars into random orbits.