Pick a style and a format, then generate a set of author names. Generate as many rounds as you like until one feels like the name on your cover.
A pen name is a long-term decision: it goes on covers, contracts with retailers and your author pages, and changing it later splits your catalogue and reviews. Choose a name that is easy to spell after hearing it once, because readers search for names they heard in conversation. Check the exact name on Amazon and Google before you commit: if another author in your genre already publishes under it, pick a different one.
Genre fit matters too. Initials read as serious or mysterious, which suits thrillers and literary fiction. Warm, full names suit romance and memoir. Whatever you choose, keep the same name across the whole series, and set up your author profiles under it before your first launch, not after.
Names are combined from common first and last name lists in your browser. Any resemblance to a real person is a coincidence, so always run the search check described above.