Bernard Vonnegut I, WAA, FAIA, (August 8, 1855 – August 7, 1908) was an American lecturer and architect active in late-nineteenth and early-twentieth-century Indiana. He was a co-founder of the locally renowned Indianapolis architectural firm of Vonnegut and Bohn, and was active in a range of residential, religious, institutional, civic, and commercial commissions. He is the namesake and grandfather of scientist Bernard Vonnegut, father of the architect Kurt Vonnegut Sr., and grandfather of author Kurt Vonnegut.