| Election Name: | Taranaki-King Country by-election, 1998 |
| Country: | New Zealand |
| Flag Year: | 1998 |
| Type: | presidential |
| Ongoing: | no |
| Previous Election: | 1996 New Zealand general election |
| Previous Year: | 1996 general |
| Next Election: | 1999 New Zealand general election |
| Next Year: | 1999 general |
| Turnout: | 20,684[1] |
| Candidate1: | Shane Ardern |
| Party1: | New Zealand National Party |
| Popular Vote1: | 5,953 |
| Percentage1: | 29.43% |
| Candidate2: | Owen Jennings |
| Party2: | ACT New Zealand |
| Popular Vote2: | 4,965 |
| Percentage2: | 24.55% |
| Candidate4: | Max Purnell |
| Party4: | New Zealand Labour Party |
| Popular Vote4: | 3,546 |
| Percentage4: | 17.53% |
| Candidate5: | Kevin Campbell |
| Party5: | Alliance (New Zealand political party) |
| Popular Vote5: | 3,208 |
| Percentage5: | 15.46% |
| Member | |
| Before Election: | Jim Bolger |
| After Election: | Shane Ardern |
| Before Party: | New Zealand National Party |
| After Party: | New Zealand National Party |
The Taranaki-King Country by-election was a by-election in the New Zealand electorate of Taranaki-King Country, a large and predominantly rural district in the west of New Zealand's North Island. It took place on 2 May 1998, and was precipitated by the resignation from parliament of sitting MP Jim Bolger. Bolger was retiring from politics, having recently been replaced as Prime Minister by Jenny Shipley.
The by-election was contested by all major parties. It was won by Shane Ardern, a member of Bolger's National Party, although Ardern gained a majority of only 988 votes. (In the 1996 general election Bolger had a majority of 10,223, or 37.37% in this seat.) Surprisingly, second place was won by Owen Jennings of the ACT party, a small party that promotes economic deregulation and other laissez-faire economic policies. The Labour Party, National's traditional opponent, was pushed back into third place. The Alliance, a left-wing party, gained fourth place. Some distance behind these four were Christian Heritage, New Zealand First, and the Greens, all with similar numbers of votes. They were followed by a group of minor parties and independents.
The following table gives the election results: