Leidos taps Rolls-Royce North America Chairman-CEO Thomas Bell as CEO, expected to be effective May 3, succeeding Roger Krone, who will retire as chairman at 2023 annual meeting, and as CEO when Bell's appointment becomes effective, but will remain a fully employed adviser through July; board expects to appoint Robert Shapard independent, nonexecutive chair after 2023 annual meeting and to nominate Bell to a board seat ... Marketing communications agency The Bliss Group promotes Cortney Stapleton to CEO.

Ipsos taps Brandwatch’s Michelle Vangel as senior vice president and head-Social Intelligence Analytics + Synthesio practice in North America ... Software platform Appian names Mark Dillon, ex-Quickbase, senior vice president-global partners organization ... Multiplatform media company a360media names Dotdash Meredith’s Andy Wilson executive vice president-chief digital officer ... Internet infrastructure company Evocative promotes Derek Garnier to CEO, succeeding founder Arman Khalili, who remains on Evocative’s board ... Vizio adds former Best Buy President-Chief Operating Officer Mike Mohan to its board.